Assessment of gain of tachycardia and bradycardia responses of cardiac baroreflex

1991 ◽  
Vol 260 (4) ◽  
pp. H1254-H1263 ◽  
Author(s):  
B. A. Kingwell ◽  
G. A. McPherson ◽  
P. I. Korner
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Logistic Function ◽  
The Other ◽  
Vasoactive Drugs ◽  
Autonomic Tone ◽  
Autonomic Changes ◽  
Logistic Functions ◽  
Perivascular Cuff

The cardiac baroreflex was studied in humans by means of vasoactive drugs and in conscious rabbits by the drug and perivascular cuff methods, which provide somewhat different afferent drive. Mean arterial pressure (MAP)-heart rate (HR) curves were derived using 1) a single symmetric logistic function and 2) a compound function, where the two halves of separate logistic functions were centered on the resting value, one for the tachycardia response and the other for the bradycardia response. There were some differences in overall reflex parameters (plateaus, HR range, gain) between the two methods because of minor degrees of asymmetry. But the differences were small, and the single symmetric logistic adequately describes the overall properties. With the compound function, we assessed average gain, Gt and Gb, for the tachycardia and bradycardia responses and the corresponding normalized (range-independent) gains, Ct and Cb. The resting HR has a large effect on Gt/Gb, since it determines the HR range of each logistic. Moreover, Gt/Gb depends on both resting autonomic tone and reflex changes. However, Ct and Cb provide information about "intrinsic" differences in sensitivity; they are independent of resting HR but entirely dependent on reflex autonomic changes. In rabbits Ct and Cb tended to be larger with the cuff than with the drug method; in addition, with the former Ct less than Cb, whereas with the drug method Ct greater than or equal to Cb, which was consistent with differences in afferent drive. There were also differences between humans and rabbits in Ct/Cb of the vagal component of the reflex. The assessment of the normalized gains of the compound logistic function has substantial advantages over previous methods for assessing gain of the tachycardia and bradycardia responses.

Differentiation of cardiac baroreflex properties by cuff and drug methods in two rabbit strains

1988 ◽  
Vol 255 (4) ◽  
pp. R654-R664 ◽  
Author(s):  
M. Weinstock ◽  
P. I. Korner ◽  
G. A. Head ◽  
P. K. Dorward
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Nonlinear Interaction ◽  
Vasoactive Drugs ◽  
Input Output ◽  
Drug Induced ◽  
Arterial Baroreceptors ◽  
Minimal Difference ◽  
The Difference

Sigmoidal mean arterial pressure (MAP)-heart rate (HR) curves were obtained in two genetically related strains of rabbits (groups I and II). We examined vagal (V) and sympathetic (S) effects on HR using perivascular cuffs and vasoactive drugs to alter MAP, and we studied the effects of intravenous naloxone, which affected only I. With the cuff method, both V and S components of gain were much greater in I than in II, and naloxone greatly reduced the difference. With the drug method, gain was similar in I and II and unaffected by naloxone. With both methods, the V component of HR range between plateaus was greater in I than in II because of more pronounced bradycardia at the lower plateau; naloxone eliminated the latter difference when the reflex was drug induced but not when it was cuff induced. The S component of HR range was similar in I and II; with both methods, the tachycardia plateau was reduced by naloxone. The cuff method alters cardiac load more than the drug method, leading to engagement of different groups of afferents for a given change in MAP (delta MAP). We have derived an input-output model, which suggests that with the drug method, gain is almost entirely determined by the input from the arterial baroreceptors, accounting for the minimal difference between I and II. With the cuff method, gain is determined by a nonlinear interaction involving the arterial and nonarterial baroreceptors, which accentuates the response. The opiate mechanism is associated with the nonarterial baroreceptor input and has amplifying properties, which account for the difference in gain between I and II. The two methods and naloxone provide a novel way of differentiating the effector patterns of the reflex; naloxone serves as a marker of activity in a particular pathway.

scholarly journals Effect of Dexmedetomidine on Perioperative Stress Response and Immune Function in Patients With Tumors

2020 ◽  
Vol 19 ◽  
pp. 153303382097754
Author(s):  
Lihong Zheng ◽  
Juan Zhao ◽  
Likun Zheng ◽  
Shuangfeng Jing ◽  
Xiaoting Wang
Keyword(s):  
Heart Rate ◽  
Stress Response ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Immune Function ◽  
Spontaneous Respiration ◽  
General Anesthetics ◽  
Ifn Γ ◽  
Group D ◽  
Perioperative Stress

Objective: This study aims to investigate the effect of dexmedetomidine on perioperative stress response and immune function in patients with tumors. Methods: Sixty patients who underwent selective radical gastrectomy for cancer were randomly divided into 3 groups: remifentanil group (group R), dexmedetomidine group (group D), and sufentanil group (group S). Remifentanil, dexmedetomidine, and sufentanil were used as general anesthetics. Endotracheal intubation and mechanical ventilation were performed after the spontaneous respiration disappeared. Then, the data were recorded, and blood samples were collected at all time points. Results: The heart rate significantly increased ( P < 0.05) at T1 in group S, and both heart rate and mean arterial pressure significantly increased ( P < 0.05) in group R when compared to group D. The heart rate significantly increased ( P < 0.05) at T2 in group S and group R. Furthermore, the heart rate significantly increased ( P < 0.05) at T3 and T4 in group S and group R. Intra-group comparison: The heart rate at T1–T4 and mean arterial pressure at T1–T4 significantly increased ( P < 0.05) in group S, and the heart rate at T1 and T4, and mean arterial pressure at T2–T4 significantly increased ( P < 0.05) in group R when compared to T0. The serum IL-6, IFN-γ, and β-EP significantly increased ( P < 0.05) at T0’ in group S and group R when compared to group D. Blood glucose, and serum IL-10, IFN-γ, and β-EP significantly increased ( P < 0.05), while IL-18 significantly decreased ( P < 0.05) at T1’ in group S and group R. Conclusion: Continuous infusion of dexmedetomidine in combination with the inhalation of sevoflurane is superior to sevoflurane + remifentanil or sufentanil in patients undergoing tumor surgery.

scholarly journals Preclinical Pharmacology in the Rhesus Monkey of CW 1759-50, a New Ultra-short Acting Nondepolarizing Neuromuscular Blocking Agent, Degraded and Antagonized by L-Cysteine

2018 ◽  
Vol 129 (5) ◽  
pp. 970-988 ◽  
Author(s):  
John J. Savarese ◽  
Hiroshi Sunaga ◽  
Jeff D. McGilvra ◽  
Matthew R. Belmont ◽  
Matthew T. Murrell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Neuromuscular Blockade ◽  
Blocking Agent ◽  
Neuromuscular Blocking ◽  
Neuromuscular Blocking Agent ◽  
Duration Of Action ◽  
Short Acting ◽  
Circulatory Effects

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Structure–activity studies were performed to identify a new neuromuscular blocking agent retaining the ultra-short acting characteristics of gantacurium, including degradation and reversal by l-cysteine, but lacking its histaminoid properties in man. CW 1759-50 has emerged from this program. Methods Adduction of CW 1759-50 with l-cysteine was studied by high-performance liquid chromatography and mass spectrometry. Institutional Animal Care and Use Committee–approved comparisons of CW 1759-50 to gantacurium were performed in rhesus monkeys. ED95 for neuromuscular blockade was established. Spontaneous recovery was compared to reversal by l-cysteine in paired studies of boluses or infusions. In addition, changes in mean arterial pressure and heart rate after very large doses of 15 to 60 × ED95 were compared. Results The half-time of adduction of l-cysteine to CW 1759-50 in vitro was 2.3 min. The ED95 of CW 1759-50 was 0.069 ± 0.02 mg/kg; ED95 of gantacurium was 0.081 ± 0.05 mg/kg (P = 0.006). Duration of action (recovery to 95% twitch height after 98 to 99% blockade) was as follows: CW 1759-50, 8.2 ± 1.5 min; and gantacurium, 7.4 ± 1.9 min; (n = 8 and 9, P = 0.355). Administration of l-cysteine (30 mg/kg) shortened recovery (i.e., induced reversal) from CW 1759-50 after boluses or infusions (P always less than 0.0001). Recovery intervals (5 to 95% twitch) ranged from 6.1 to 6.7 min (and did not differ significantly) after boluses of 0.10 to 0.50 mg/kg, as well as control infusions (P = 0.426 by analysis of variance). Dose ratios comparing changes of 30% in mean arterial pressure or heart rate to ED95 for neuromuscular blockade (ED 30% Δ [mean arterial pressure or heart rate]/ED95) were higher for CW 1759-50 than for gantacurium. Conclusions CW 1759-50, similar to gantacurium, is an ultra-short acting neuromuscular blocking agent, antagonized by l-cysteine, in the monkey. The circulatory effects, however, are much reduced in comparison with gantacurium, suggesting a trial in humans.

Hypotensive and Regional Haemodynamic Effects of Exercise, Fasted and after Food, in Human Sympathetic Denervation

1998 ◽  
Vol 94 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Sharmini Puvi-Rajasingham ◽  
Gareth D. P. Smith ◽  
Adeola Akinola ◽  
Christopher J. Mathias
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Superior Mesenteric Artery ◽  
Vascular Resistance ◽  
Mesenteric Artery ◽  
Autonomic Failure ◽  
Sympathetic Denervation ◽  
Stroke Distance

1. In human sympathetic denervation due to primary autonomic failure, food and exercise in combination may produce a cumulative blood pressure lowering effect due to simultaneous splanchnic and skeletal muscle dilatation unopposed by corrective cardiovascular reflexes. We studied 12 patients with autonomic failure during and after 9 min of supine exercise, when fasted and after a liquid meal. Standing blood pressure was also measured before and after exercise. 2. When fasted, blood pressure fell during exercise from 162 ± 7/92 ± 4 to 129 ± 9/70 ± 5 mmHg (mean arterial pressure by 22 ± 5%), P < 0.0005. After the meal, blood pressure fell from 159 ± 8/88 ± 6 to 129 ± 6/70 ± 4 mmHg (mean arterial pressure by 22 ± 3%), P < 0.0001, and further during exercise to 123 ± 6/61 ± 3 mmHg (mean arterial pressure by 9 ± 3%), P < 0.01. The stroke distance—heart rate product, an index of cardiac output, did not change after the meal. During exercise, changes in the stroke distance—heart rate product were greater when fasted. 3. Resting forearm and calf vascular resistance were higher when fasted. Calf vascular resistance fell further after exercise when fasted. Resting superior mesenteric artery vascular resistance was lower when fed; 0.19 ± 0.02 compared with 032 ± 0.06, P < 0.05. After exercise, superior mesenteric artery vascular resistance had risen by 82%, to 0.53 ± 0.12, P < 0.05 (fasted) and by 47%, to 0.29 ± 0.05, P < 0.05 (fed). 4. On standing, absolute levels of blood pressure were higher when fasted [83 ± 7/52 ± 7 compared with 71 ± 2/41 ± 3 (fed), each P < 0.05]. Subjects were more symptomatic on standing post-exercise when fed. 5. In human sympathetic denervation, exercise in the fed state lowered blood pressure further than when fasted and worsened symptoms of postural hypotension.

Angiotensin II induces insulin resistance independent of changes in interstitial insulin

1999 ◽  
Vol 277 (5) ◽  
pp. E920-E926 ◽  
Author(s):  
Joyce M. Richey ◽  
Marilyn Ader ◽  
Donna Moore ◽  
Richard N. Bergman
Keyword(s):  
Insulin Resistance ◽  
Heart Rate ◽  
Blood Flow ◽  
Angiotensin Ii ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Glucose Uptake ◽  
Peripheral Resistance ◽  
Glucose Turnover ◽  
Ang Ii

We set out to examine whether angiotensin-driven hypertension can alter insulin action and whether these changes are reflected as changes in interstitial insulin (the signal to which insulin-sensitive cells respond to increase glucose uptake). To this end, we measured hemodynamic parameters, glucose turnover, and insulin dynamics in both plasma and interstitial fluid (lymph) during hyperinsulinemic euglycemic clamps in anesthetized dogs, with or without simultaneous infusions of angiotensin II (ANG II). Hyperinsulinemia per se failed to alter mean arterial pressure, heart rate, or femoral blood flow. ANG II infusion resulted in increased mean arterial pressure (68 ± 16 to 94 ± 14 mmHg, P < 0.001) with a compensatory decrease in heart rate (110 ± 7 vs. 86 ± 4 mmHg, P < 0.05). Peripheral resistance was significantly increased by ANG II from 0.434 to 0.507 mmHg ⋅ ml−1⋅ min ( P < 0.05). ANG II infusion increased femoral artery blood flow (176 ± 4 to 187 ± 5 ml/min, P < 0.05) and resulted in additional increases in both plasma and lymph insulin (93 ± 20 to 122 ± 13 μU/ml and 30 ± 4 to 45 ± 8 μU/ml, P < 0.05). However, glucose uptake was not significantly altered and actually had a tendency to be lower (5.9 ± 1.2 vs. 5.4 ± 0.7 mg ⋅ kg−1⋅ min−1, P > 0.10). Mimicking of the ANG II-induced hyperinsulinemia resulted in an additional increase in glucose uptake. These data imply that ANG II induces insulin resistance by an effect independent of a reduction in interstitial insulin.

Preclinical Pharmacology of CW002

2016 ◽  
Vol 125 (4) ◽  
pp. 732-743 ◽  
Author(s):  
Hiroshi Sunaga ◽  
John J. Savarese ◽  
Jeff D. McGilvra ◽  
Paul M. Heerdt ◽  
Matthew R. Belmont ◽  
...  
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Blocking Agent ◽  
Neuromuscular Blocking ◽  
Safety And Efficacy ◽  
Circulatory Effects ◽  
Autonomic Changes ◽  
Train Of Four

Abstract Background CW002, a novel nondepolarizing neuromuscular blocking agent of intermediate duration, is degraded in vitro by l-cysteine; CW002-induced neuromuscular blockade (NMB) is antagonized in vivo by exogenous l-cysteine.1 Further, Institutional Animal Care and Use Committee–approved studies of safety and efficacy in eight anesthetized monkeys and six cats are described. Methods Mean arterial pressure, heart rate, twitch, and train-of-four were recorded; estimated dose producing 95% twitch inhibition (ED95) for NMB and twitch recovery intervals from 5 to 95% of baseline were derived. Antagonism of 99 to 100% block in monkeys by l-cysteine (50 mg/kg) was tested after bolus doses of approximately 3.75 to 20 × ED95 and after infusions. Vagal and sympathetic autonomic responses were recorded in cats. Dose ratios for [circulatory (ED20) or autonomic (ED50) changes/ED95 (NMB)] were calculated. Results ED95s of CW002 in monkeys and cats were 0.040 and 0.035 mg/kg; l-cysteine readily antagonized block in monkeys: 5 to 95% twitch recovery intervals were shortened to 1.8 to 3.6 min after 3.75 to 10 × ED95 or infusions versus 11.5 to 13.5 min during spontaneous recovery. ED for 20% decrease of mean arterial pressure (n = 27) was 1.06 mg/kg in monkeys; ED for 20% increase of HR (n = 27) was 2.16 mg/kg. ED50s for vagal and sympathetic inhibition in cats were 0.59 and &gt;&gt;0.80 mg/kg (n = 14 and 15). Dose ratios for [circulatory or autonomic changes/ED95 (NMB)] were all more than 15 × ED95. Conclusions The data further verify the neuromuscular blocking properties of CW002, including rapid reversal by l-cysteine of 100% NMB under several circumstances. A notable lack of autonomic or circulatory effects provided added proof of safety and efficacy.

scholarly journals EFFECT OF ORAL MOXONIDINE IN THE ATTENUATION OF THE HAEMODYNAMIC RESPONSES SEEN DURING LAPAROSCOPIC SURGERIES

2017 ◽  
Vol 10 (3) ◽  
pp. 409
Author(s):  
Sidharth Sraban Routray ◽  
Ramakanta Mohanty
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Placebo Group ◽  
Stress Response ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Significant Rise ◽  
Hemodynamic Stability ◽  
Blinded Study ◽  
Double Blinded

ABSTRACTObjective: During laparoscopic surgeries, pneumoperitoneum can lead to various pathophysiologic changes in the cardiovascular system resulting inhypertension and tachycardia. Search for ideal drug to prevent this hemodynamic response goes on. The aim of our study was to evaluate the effect oforally administered moxonidine in attenuating the hemodynamic responses that occur during the laparoscopic surgeries.Methods: A total of 50 adult acetylsalicylic acid I and II patients scheduled for elective laparoscopic surgeries were selected for this prospectiverandomized double-blinded study. They were randomly allocated into two groups: moxonidine group (M) and placebo group (P). M group receivedoral moxonidine 0.3 mg at 8 pm on the day before surgery and at 8 am on the day of surgery. P group received a placebo at the same timing as that ofthe M group.Results: Following pneumoperitoneum rise in systolic blood pressure (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and heart rate (HR)was higher in P group in comparison to M group which was statistically significant.Conclusion: Significant rise in HR, SBP, DBP, and mean BP was noted in the P group in comparison to moxonidine group. Moxonidine provided betterperioperative hemodynamic stability in patients undergoing laparoscopic surgeries.Keywords: Moxonidine, Stress response, Laparoscopic.

scholarly journals Multifractal Analysis of Hemodynamic Behavior

2012 ◽  
Vol 117 (4) ◽  
pp. 810-821 ◽  
Author(s):  
Steven M. Bishop ◽  
Sarah I. Yarham ◽  
Vilas U. Navapurkar ◽  
David K. Menon ◽  
Ari Ercole
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
De Novo ◽  
Clinical Importance ◽  
Multifractal Spectrum ◽  
Clinical Problem ◽  
Abdominal Aortic Aneurysm Repair ◽  
Feedback Systems ◽  
Modulus Maxima

Background Physiologic instability is a common clinical problem in the critically ill. Many natural feedback systems are nonlinear, and seemingly random fluctuations may result from the amplification of external perturbations or even arise de novo as a consequence of their underlying dynamics. Characterization of the underlying nonlinear state may be of clinical importance, providing a technique to monitor complex physiology in real-time, guiding patient care and improving outcomes. Methods We employ the wavelet modulus maxima technique to characterize the multifractal properties of heart rate and mean arterial pressure physiology retrospectively for four patients during open abdominal aortic aneurysm repair. We calculated point-estimates for the dominant Hölder exponent (hm, hm) and multifractal spectrum width-at-half-height for both heart rate and mean arterial pressure signals. We investigated how these parameters changed with the administration of an intravenous vasoconstrictor and examined how this varied with atropine pretreatment. Results Hypotensive patients showed lower values of hm, consistent with a more highly fluctuating and complex behavior. Treatment with a vasoconstrictor led to a transient increase in hm, revealing the appearance of longer-range correlations, but did not impact hm. On the other hand, prior treatment with atropine had no effect on hm behavior but did tend to increase hm. Conclusions Hypotension leads to a reduction in dominant Hölder exponents for mean arterial pressure, demonstrating an increasing signal complexity consistent with the activation of important homeokinetic processes. Conversely, pharmacological interventions may also alter the underlying dynamics. Pharmacological restoration of homeostasis leads to system decomplexification, suggesting that homeokinetic mechanisms are derecruited as homeostasis is restored.

scholarly journals Perbedaan Respon Hemodinamik dengan Penambahan Blok Scalp Levobupivakain pada Operasi Kraniotomi

2020 ◽  
Vol 9 (1) ◽  
pp. 8-15
Author(s):  
Arya Justisia Sani ◽  
Ardhana Tri Arianto ◽  
Muhammad Husni Thamrin
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Hemodynamic Response ◽  
Anesthesia Induction ◽  
Group I ◽  
Significant Difference ◽  
Scalp Block ◽  
One Way Anova

Latar Belakang dan Tujuan: Peningkatan respon hemodinamik yang disebabkan oleh nyeri dapat menyebabkan peningkatan aliran darah otak dan tekanan intrakranial. Blok scalp pada kraniotomi menumpulkan respon hemodinamik karena rangsangan nyeri serta mengurangi penambahan analgesi lain. Penelitian ini bertujuan untuk mengetahui efektifitas blok scalp sebagai analgetik pada kraniotomi.Subjek dan Metode: Penelitian ini menggunakan uji klinik acak tersamar ganda pada 36 pasien dengan status fisik ASA 1–3 dilakukan operasi kraniotomi eksisi dan memenuhi kriteria inklusi. Sampel dibagi menjadi kelompok I (dengan blok scalp) dan kelompok II (tanpa blok scalp). Blok dilakukan sesaat setelah induksi anestesi. Digunakan levobupivakain 0,375% sebanyak 3 ml tiap insersi, pada masing-masing saraf. Tekanan darah, tekanan arteri rata-rata, detak jantung sebelum intubasi dan setelah intubasi, pemasangan pin, insisi kulit dan insisi duramater serta total kebutuhan fentanyl tambahan dicatat. Data yang diperoleh dianalisis dengan program komputer SPSS versi 17 lalu diuji menggunakan uji Kruskal-Wallis atau One-way ANOVA. Batas kemaknaan yang diambil adalah p < 0,05.Hasil: Selama kraniotomi, detak jantung, tekanan darah, tekanan arteri rata-rata secara signifikan lebih tinggi pada pasien tanpa blok scalp terutama pada saat pemasangan pin. Hasil uji statistik menunjukkan perbedaan signifikan, penambahan fentanyl pada pasien dengan blok scalp lebih sedikit dibandingkan tanpa blok scalp, p=0,000 (p<0,05).Simpulan: Blok scalp levobupivakain efektif dalam menurunkan respon hemodinamik terutama pada saat pemasangan pin. Pasien kraniotomi dengan blok scalp membutuhkan penambahan fentanyl lebih sedikit. Differences on Hemodynamic Response with Levobupivacaine Scalp Block in Craniotomy SurgeryAbstractBackground and Objective: Increased hemodynamic response caused by pain can lead to increased cerebral blood flow and intracranial pressure. Scalp block in craniotomy blunts hemodynamic response due to pain and reduce other analgesics addition. This study aims to determine effectiveness of scalp blocks as analgesic in craniotomy.Subject and Method: This study used a double-blind randomized clinical trial in 36 patients with physical status ASA 1-3 who underwent craniotomy and met inclusion criteria. Samples were divided into group I (with scalp block) and group II (without scalp block). Scalp Block was performed right after anesthesia induction. Using levobupivacaine 0.375% 3 ml for each insertion. Blood pressure, mean arterial pressure, heart rate before and after intubation, during pin placement, skin incision and duramater incision and total need for additional fentanyl were recorded. SPSS version 17 was used and data were analysed using Kruskal-Wallis or One-way ANOVA. Statistical significance was accepted at p < 0.05.Result: During craniotomy, heart rate, blood pressure, mean arterial pressure were significantly higher in patients without scalp block especially during pin placement. Statistical test showed significant difference, additional fentanyl in patients with scalp blocks was lesser, p = 0.000 (p <0.05). Conclusion: Levobupivacaine scalp block was effective to blunt hemodynamic response especially during pin placement. Scalp block also decreased additional fentanyl in craniotomy.

Renal Denervation Prevents Sodium Retention and Hypertension in Salt-Sensitive Rabbits with Genetic Baroreflex Impairment

1996 ◽  
Vol 90 (4) ◽  
pp. 287-293 ◽  
Author(s):  
Marta Weinstock ◽  
Elena Gorodetsky ◽  
Ronald Kalman
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Plasma Renin Activity ◽  
Renal Denervation ◽  
Plasma Renin ◽  
High Salt ◽  
Renin Activity ◽  
Group I ◽  
Group Ii

1. Rabbits with a genetic impairment in baroreflex control of heart rate become hypertensive on a high salt diet. The present study determined the effect of bilateral renal denervation on blood pressure and sodium balance after salt loading (four times normal intake; 28–36 mEq NaCl/day) in normotensive rabbits with high (Group I) and low (Group II) baroreflex sensitivity, respectively. 2. Eight rabbits in each group were denervated or sham-denervated 1 week before commencement of the high salt diet. Before operation, the two groups differed only in the gain of their cardiac baroreflex (Group I, −6.4 ± 0.4 beats min−1 mmHg−1; Group II, −3.2 ± 0.15 beats min−1 mmHg−1). 3. In Group I sham-denervated rabbits, mean arterial pressure remained unchanged, and plasma renin activity and heart rate fell significantly in response to the high salt. In Group II sham-denervated rabbits, mean arterial pressure increased by 10.6 ± 1.2 mmHg, and heart rate and plasma renin activity remained unchanged. Their cumulative Na+ retention and weight gain was more than twice that of Group I sham-denervated rabbits. 4. Renal denervation decreased plasma renin activity in both groups to <1 pmol Ang I h−1 ml−1, lowered cumulative Na+ retention from 102 ± 4 to 35 ± 5 mEq (P<0.01) and completely prevented the increase in mean arterial pressure in response to high salt in Group II. 5. The results suggest that Group II rabbits retain salt and fluid in response to their diet because of an abnormality in their control of renal nerve activity, possibly via vagal afferents. This results in blood pressure elevation because of an inability to lower peripheral resistance and heart rate in response to the increase in cardiac output. 6. Since they display several of the characteristics of salt-sensitive hypertensive humans, i.e. salt retention, normal plasma renin activity, but abnormal regulation of plasma renin activity and blood flow in response to salt loading, Group II are an appropriate model of human salt-induced hypertension.

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