Influence of muscle length and force on endurance and pressor responses to isometric exercise

1994 ◽  
Vol 76 (6) ◽  
pp. 2561-2569 ◽  
Author(s):  
A. V. Ng ◽  
J. C. Agre ◽  
P. Hanson ◽  
M. S. Harrington ◽  
F. J. Nagle
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Muscle Length ◽  
Cardiovascular Responses ◽  
Knee Extension ◽  
Endurance Time ◽  
External Torque ◽  
Significant Difference ◽  
Isometric Knee Extension

Experiments were performed to determine whether endurance time, mean arterial pressure, or heart rate was related to either muscle length or external torque production in humans during isometric knee extension. Eight men and nine women performed isometric knee extension to the endurance limit at each of three muscle lengths, determined by knee angles of 40 degrees (0.698 rad, shortest), 60 degrees (1.047 rad, intermediate), and 90 degrees (1.571 rad, longest), and at intensities of 30 and 50% maximal voluntary contraction (MVC). Knee extension forms an ascending-descending length-torque curve, and lengths were chosen to result in different external torques. MVC was greatest at a knee angle of 60 degrees (P < 0.05 vs. 40 degrees, 90 degrees), with no significant difference between 90 degrees and 40 degrees. Endurance time was inversely related to muscle length, independent of torque production, at 30% MVC [40 degrees, 395 +/- 139 (SE); 60 degrees, 237 +/- 60; 90 degrees, 165 +/- 51 s; P < 0.05 vs. each other] and 50% MVC (40 degrees, 176 +/- 64; 60 degrees, 137 +/- 40; 90 degrees, 85 +/- 23 s; P < 0.05 vs. each other). Evidence is presented that endurance is a function of internal muscle force and not resultant external torque. The experimental design allowed the relationship of external torque and cardiovascular responses to be examined independent of exercise intensity. Muscle mass was also controlled in that the same muscle group was involved in all contractions. There were no differences in mean arterial pressure, heart rate, or rating of perceived exertion at any percentage of endurance time under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of regular voluntary exercise on resting cardiovascular responses in SHR and WKY pregnant rats

1992 ◽  
Vol 73 (2) ◽  
pp. 713-720 ◽  
Author(s):  
M. T. Jones ◽  
K. I. Norton ◽  
D. M. Black ◽  
R. E. Graham ◽  
R. B. Armstrong
Keyword(s):  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Cytochrome C ◽  
Arterial Pressure ◽  
Vastus Lateralis ◽  
Cardiovascular Responses ◽  
Voluntary Exercise ◽  
Uterine Blood Flow ◽  
Pregnant Rats ◽  
Significant Difference

The purpose of this study was to assess the influence of regular voluntary exercise in pregnant normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats on 1) uteroplacental perfusion and mean arterial pressure in the resting conscious condition and 2) fetal number, fetal weight, and number of fetal resorptions. WKYs and SHRs were randomly assigned to standard cages [CWKY (n = 10); CSHR (n = 6)] or cages with activity wheels [EWKY (n = 7); ESHR (n = 8)]. EWKYs and ESHRs exercised for 12 wk, and then all rats were bred and experiments were conducted on gestational day 17. Resting blood flow (microspheres), heart rate (HR), and mean arterial pressure (Pa) were measured. No significant difference was found in Pa, HR, uterine blood flow (ESHRs 52 +/- 8 ml.min-1.100 g-1; CSHRs 28 +/- 6 ml.min-1.100 g-1), or maternal placental blood flow (ESHRs, 122 +/- 31 ml.min-1.100 g-1; CSHRs 78 +/- 21 ml.min-1.100 g-1) among the groups. Exercise altered the relationship between maternal placental and uterine blood flow and Pa in the SHR; SHRs with lower Pa maintained higher placental and uterine blood flow after training. Before gestation ESHRs ran on average more kilometers per week than EWKYs (43 +/- 3 vs. 34 +/- 4), but during gestation ESHRs averaged fewer kilometers per week than EWKYs (16 +/- 4 vs. 22 +/- 4). Succinate dehydrogenase activity was higher in the white vastus lateralis (1.02 +/- 0.2 mumol cytochrome c reduced.min-1.g wet wt-1) and vastus intermedius (3.1 +/- 0.5 mumol cytochrome c reduced.min-1.g wet wt-1) muscles of ESHRs.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Naturally occurring hypertension in New World nonhuman primates: potential role of the perifornical hypothalamus

2007 ◽  
Vol 292 (2) ◽  
pp. R937-R945 ◽  
Author(s):  
Orville A. Smith ◽  
Cliff A. Astley
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
New World ◽  
Critical Role ◽  
Cardiovascular Responses ◽  
Routine Laboratory ◽  
New World Primates ◽  
Naturally Occurring

Hypertension is a prominent underlying factor in the genesis of cardiovascular-related morbidity and mortality. A major impediment to the investigation into the causes of the disease is the paucity of naturally occurring animal models of the disease. There is evidence that some species of New World primates spontaneously become hypertensive. We used chronically implanted pressure transducers to assess normally occurring blood pressure and heart rate levels at rest and during routine laboratory procedures in a group of one of these New World primates ( Aotus sp.). Resting mean arterial pressure ranged from 72 to 130 mmHg. Three animals were judged to have resting mean arterial pressure levels in the hypertensive range (≥110 mmHg). In all of the animals, pressor responses to routine laboratory events were exaggerated (average highest mean pressure during 1 min from any session was 97–196 mmHg). Subsequently, the region of the perifornical/lateral hypothalamus known to produce elevated blood pressure and heart rate responses to electrical stimulation was removed, and the blood pressure responses to the laboratory routines were significantly decreased and, in some cases, eliminated. Control lesions in nearby tissue had no effect on these responses. This region may play a critical role in initiating or exacerbating cardiovascular responses that contribute to the development of essential hypertension.

Effects of Ambulation and Nondependent Transfers on Vital Signs in Patients Receiving Norepinephrine

2017 ◽  
Vol 26 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Rosario Arcaya Nievera ◽  
Ann Fick ◽  
Hilary K. Harris
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Physical Therapy ◽  
Arterial Pressure ◽  
Low Dose ◽  
Vital Signs ◽  
Activity Level ◽  
Significant Difference ◽  
Before And After ◽  
Norepinephrine Dose

Purpose To assess the safety of mobilizing patients receiving low-dose norepinephrine (0.05 μg/kg per min) by examining mean arterial pressure and heart rate before and after activity with parameters set by the physician. Background Norepinephrine is a peripheral vasoconstrictor administered for acute hypotension. During activity, blood flows to the periphery to supply muscles with oxygen, which may oppose the norepinephrine vasoconstriction. The safety of mobilizing patients receiving norepinephrine is unclear. Methods Heart rate, mean arterial pressure, norepinephrine dose, and activity performed were extracted retrospectively from charts of 47 cardiothoracic surgery patients during the first patient transfer to chair or ambulation with norepinephrine infusing. Mean arterial pressure and heart rate were compared before and after physical therapy (paired t tests). Differences among norepinephrine doses and physical activity levels were evaluated (Kruskal-Wallis test). Results Forty-one of the 47 patients (87%) tolerated the activity within safe ranges of vital signs. The change in patients’ mean arterial pressure from before to after activity was not significant (P = .16), but a significant increase in heart rate occurred after activity (P &lt; .001). A Kruskal-Wallis test showed no significant difference in the norepinephrine dose and activity level (χ2 = 6.34, P = .17). No instances of cardiopulmonary or respiratory arrest occurred during any physical therapy sessions. Conclusions Infusion of low-dose norepinephrine should not be considered an automatic reason to keep patients on bed rest.

A Non-inferiority Trial: Safety and Efficacy of Topical 1:1000 versus 1:10 000 Epinephrine in Sino-nasal Surgeries

2020 ◽  
pp. 000348942096282
Author(s):  
Cassie L. Dow ◽  
Anders W. Sideris ◽  
Ravjit Singh ◽  
Mitchell H. Giles ◽  
Catherine Banks ◽  
...  
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Nasal Passage ◽  
Hemodynamic Parameters ◽  
Hemodynamic Stability ◽  
Absolute Change ◽  
Significant Difference ◽  
Blood Pressures ◽  
Surgical Conditions

Objective: This study aimed to test the non-inferiority of topical 1:1000 epinephrine compared to topical 1:10 000 with regard to intraoperative hemodynamic stability, and to determine whether it produced superior visibility conditions. Methods: A single-blinded, prospective, cross-over non-inferiority trial was performed. Topical 1:1000 or topical 1:10 000 was placed in 1 nasal passage. Hemodynamic parameters (heart rate, systolic and diastolic blood pressures, and mean arterial pressure) were measured prior to insertion then every minute for 10 minutes. This was repeated in the contralateral nasal passage of the same patient with the alternate concentration. The surgeon graded the visualization of each passage using the Boezaart Scale. The medians of the greatest absolute change in parameters were compared using a Wilcoxon Rank-Signed test and confidence intervals were calculated using a Hodges-Lehman test. The non-inferiority margin was pre-determined at 10 bpm for heart rate and 10 mmHg for blood pressures. A Wilcoxon Rank-Signed test was used to assess superiority in visualization. Results: Thirty-two patients were enrolled and after exclusions, nineteen were assessed (mean age = 35.63 ± 12.49). Differences in means of greatest absolute change between the 2 concentrations were calculated (heart rate = 2.49 ± 1.20; systolic = −1.51 ± 2.16; diastolic = 2.47 ± 1.47; mean arterial pressure = 0.07 ± 1.83). In analyses of medians, 1:1000 was non-inferior to the 1:10 000. There was a significant difference (–0.58 ± 0.84; P = .012) in visualization in favor of topical 1:1000. Conclusion: Topical 1:1000 epinephrine provides no worse intraoperative hemodynamic stability compared to topical 1:10 000 but affords superior visualization and should be used to optimize surgical conditions.

Neuronal and cardiovascular responses to ANF microinjected into the solitary nucleus

1989 ◽  
Vol 256 (2) ◽  
pp. R577-R582 ◽  
Author(s):  
R. Ermirio ◽  
P. Ruggeri ◽  
C. E. Cogo ◽  
C. Molinari ◽  
F. R. Calaresu
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Unit Activity ◽  
Atrial Natriuretic Factor ◽  
Single Unit ◽  
Cardiovascular Responses ◽  
Firing Frequency ◽  
Neuronal Firing ◽  
Single Unit Activity

The effect on single-unit activity, arterial pressure, and heart rate of a microinjection of atrial natriuretic factor (ANF) into 78 histologically verified sites in the nucleus tractus solitarii (NTS) was investigated in rats. Injections of 50 nl of 10(-7) M ANF excited 34 neurons (44%), mainly localized at the level of the obex, inhibited 15 (19%), and had no effect on the remaining 29 (37%). The increase in firing frequency of the 34 excited neurons was always followed by a decline in mean arterial pressure [MAP, -10.6 +/- 1.8 (SE) mmHg; P less than 0.01] and heart rate [HR, -9.6 +/- 3.1 (SE) beats/min; P less than 0.05]. When injections of ANF caused either no effect or inhibition of single-unit activity, no changes in either MAP or HR were observed. Single units excited by injections of ANF were also excited by activation of arterial baroreceptors and inhibited by baroreceptor unloading. Control injections of an inactive peptide analogue of ANF or of vehicle never produced any effects on neuronal firing frequency or on MAP and HR. Similar results were obtained from animals paralyzed and artificially ventilated. These results support the hypothesis that ANF plays a role in the chemical transmission of baroreceptor information within the NTS.

Maternal responses to long-term hypoxemia in sheep

1989 ◽  
Vol 256 (6) ◽  
pp. R1340-R1347 ◽  
Author(s):  
T. Kitanaka ◽  
R. D. Gilbert ◽  
L. D. Longo
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Blood Volume ◽  
Cardiovascular Responses ◽  
Uterine Blood Flow ◽  
O2 Uptake ◽  
Arterial Po2

To determine the maternal cardiovascular responses to long-term hypoxemia, we studied three groups of animals: 1) pregnant ewes (n = 20) at 110-115 days gestation subjected to hypoxia for up to 28 days; 2) pregnant ewes (n = 4) that served as normoxic controls; and 3) nonpregnant ewes (n = 6) subjected to hypoxemia for up to 28 days. We measured mean arterial pressure, heart rate, uterine blood flow, and uterine vascular resistance continuously for 1 h/day while the ewe was exposed to an inspired O2 fraction of 12-13% for at least 17 days. Arterial PO2, O2 saturation, hemoglobin, arteriovenous O2 difference, and uterine O2 uptake were measured daily while blood volume and erythropoietin concentration were measured weekly. In the pregnant hypoxic group arterial PO2 decreased from a control value of 101.5 +/- 5.1 to 59.2 +/- 5.1 Torr within a few minutes, where it remained throughout the study. The hemoglobin concentration increased from 8.9 +/- 0.5 to 10.0 +/- 0.5 g/dl within 24 h where it remained, whereas erythropoietin concentration increased from 16.6 +/- 2.1 to 39.1 +/- 7.8 mU/ml at 24 h but then returned to near-control levels. Arterial glucose concentration, mean arterial pressure, and cardiac output decreased slightly but insignificantly. In contrast, body weight, heart rate, blood volume, uterine blood flow, uterine O2 flow, uteroplacental O2 uptake, and the concentrations of catecholamines and cortisol remained relatively constant. Thus both pregnant and nonpregnant sheep experience relatively minor cardiovascular and hematologic responses in response to long-term hypoxemia of moderate severity.

Spinal action of neurokinins in the rat: effects on mean arterial pressure, heart rate, and vascular permeability

1987 ◽  
Vol 65 (11) ◽  
pp. 2182-2187 ◽  
Author(s):  
Harout Hasséssian ◽  
Réjean Couture ◽  
Line Jacques
Keyword(s):  
Spinal Cord ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Permeability ◽  
Cardiovascular Responses ◽  
Intrathecal Administration ◽  
Water Soluble ◽  
Neurokinin A ◽  
Anaesthetized Rats

In urethane-anaesthetized rats, the intrathecal administration of 6.5 nmol of substance P (SP), neurokinin A (NKA), or neurokinin B (NKB) at the T8–T10 level of the spinal cord enhances mean arterial pressure and heart rate. However, in the pentobarbital-anaesthetized rat, while NKB produces no effect on mean arterial pressure, NKA produces a biphasic change and SP, a depressor response. All three neurokinins elicit a tachycardia. The following rank order of potency SP ≥ NKA > NKB is observed in relation to these cardiovascular responses when either one of the two anaesthetics is used. The low cardiovascular activity of NKB cannot be attributed to its hydrophobicity, as the water soluble analogue of NKB, [Arg0] NKB, elicits a response as weak as the native peptide. In pentobarbital-anaesthetized rats, the intrathecal administration of 6.5 nmol of SP, also enhances plasma protein extravasation in cutaneous tissues of the back, the hind paws, and the ears. In this response NKA and NKB are either inactive (skin of hind paws) or less potent than SP (ears and dorsal skin). These findings agree with the hypothesis that in the rat spinal cord, the neurokinin receptor producing changes in mean arterial pressure, heart rate, and vascular permeability is of the NK-1 subtype.

Stimulation of NPY Y2 receptors by PYY3-36 reveals divergent cardiovascular effects of endogenous NPY in rats on different dietary regimens

2004 ◽  
Vol 286 (1) ◽  
pp. R138-R142 ◽  
Author(s):  
Ulrich Nordheim ◽  
Karl G. Hofbauer
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
High Fat Diet ◽  
Cardiovascular Effects ◽  
Cardiovascular Responses ◽  
Chow Diet ◽  
High Fat ◽  
Standard Chow Diet ◽  
Ad Libitum

In the present experiments the gut hormone peptide YY3-36 (PYY3-36), which inhibits neuropeptide Y (NPY) release, was used as a tool to study the cardiovascular effects of endogenous NPY under different dietary regimens in rats instrumented with a telemetry transmitter. In a first experiment, rats were placed on a standard chow diet ad libitum and in a second experiment on a high-fat diet ad libitum. After 6 wk, PYY3-36 (300 μg/kg) or vehicle was injected intraperitoneally. In a third experiment, PYY3-36 or vehicle was administered after 14 days of 50% restriction of a standard chow diet. In food-restricted rats, PYY3-36 increased mean arterial pressure (7 ± 1 mmHg, mean ± SE, P < 0.001 vs. saline, 1-way repeated-measures ANOVA with Bonferroni t-test) and heart rate (22 ± 4 beats/min, P < 0.001) during 3 h after administration. Conversely, PYY3-36 did not influence mean arterial pressure (0 ± 1 mmHg) and heart rate (-8 ± 5 beats/min) significantly in rats on a high-fat diet. Rats fed standard chow diet ad libitum showed an intermediate response (mean arterial pressure 4 ± 1 mmHg, P < 0.05, and heart rate 5 ± 2 beats/min, not significant). Thus, in our studies, divergent cardiovascular responses to PYY3-36 were observed in rats on different dietary regimens. These findings suggest that the cardiovascular effects of PYY3-36 depend on the hypothalamic NPY release, which is increased after chronic food restriction and decreased during a high-fat diet.

scholarly journals Abnormal cardiovascular response to nitroglycerin in migraine

Cephalalgia ◽  
2019 ◽  
Vol 40 (3) ◽  
pp. 266-277
Author(s):  
Willebrordus PJ van Oosterhout ◽  
Guus G Schoonman ◽  
Dirk P Saal ◽  
Roland D Thijs ◽  
Michel D Ferrari ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Total Peripheral Resistance ◽  
Cardiovascular Response ◽  
Peripheral Resistance ◽  
Cardiovascular Responses ◽  
Initial Increase

Introduction Migraine and vasovagal syncope are comorbid conditions that may share part of their pathophysiology through autonomic control of the systemic circulation. Nitroglycerin can trigger both syncope and migraine attacks, suggesting enhanced systemic sensitivity in migraine. We aimed to determine the cardiovascular responses to nitroglycerin in migraine. Methods In 16 women with migraine without aura and 10 age- and gender-matched controls without headache, intravenous nitroglycerin (0.5 µg·kg−1·min−1) was administered. Finger photoplethysmography continuously assessed cardiovascular parameters (mean arterial pressure, heart rate, cardiac output, stroke volume and total peripheral resistance) before, during and after nitroglycerin infusion. Results Nitroglycerin provoked a migraine-like attack in 13/16 (81.2%) migraineurs but not in controls ( p = .0001). No syncope was provoked. Migraineurs who later developed a migraine-like attack showed different responses in all parameters vs. controls (all p < .001): The decreases in cardiac output and stroke volume were more rapid and longer lasting, heart rate increased, mean arterial pressure and total peripheral resistance were higher and decreased steeply after an initial increase. Discussion Migraineurs who developed a migraine-like attack in response to nitroglycerin showed stronger systemic cardiovascular responses compared to non-headache controls. The stronger systemic cardiovascular responses in migraine suggest increased systemic sensitivity to vasodilators, possibly due to insufficient autonomic compensatory mechanisms.

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