scholarly journals Renal and segmental artery hemodynamics during whole body passive heating and cooling recovery

2019 ◽  
Vol 127 (4) ◽  
pp. 974-983 ◽  
Author(s):  
Christopher L. Chapman ◽  
Julia M. Benati ◽  
Blair D. Johnson ◽  
Nicole T. Vargas ◽  
Penelope C. Lema ◽  
...  
Keyword(s):  
Renal Artery ◽  
Core Temperature ◽  
Vascular Resistance ◽  
Cold Pressor Test ◽  
Cold Pressor ◽  
Blood Velocity ◽  
Sympathetic Activation ◽  
Passive Heating ◽  
Segmental Artery ◽  
Renal Vascular

High environmental temperatures are associated with increased risk of acute kidney injury, which may be related to reductions in renal blood flow. The susceptibility of the kidneys may be increased because of heat stress-induced changes in renal vascular resistance (RVR) to sympathetic activation. We tested the hypotheses that, compared with normothermia, increases in RVR during the cold pressor test (CPT, a sympathoexcitatory maneuver) are attenuated during passive heating and exacerbated after cooling recovery. Twenty-four healthy adults (22 ± 2 yr; 12 women, 12 men) completed CPTs at normothermic baseline, after passive heating to a rise in core temperature of ~1.2°C, and after cooling recovery when core temperature returned to ~0.2°C above normothermic baseline. Blood velocity was measured by Doppler ultrasound in the distal segment of the right renal artery (Renal, n = 24 during thermal stress, n = 12 during CPTs) or the middle portion of a segmental artery (Segmental, n = 12). RVR was calculated as mean arterial pressure divided by renal or segmental blood velocity. RVR increased at the end of CPT during normothermic baseline in both arteries (Renal: by 1.0 ± 1.0 mmHg·cm−1·s, Segmental: by 2.2 ± 1.2 mmHg·cm−1·s, P ≤ 0.03), and these increases were abolished with passive heating ( P ≥ 0.76). At the end of cooling recovery, RVR in both arteries to the CPT was restored to that of normothermic baseline ( P ≤ 0.17). These data show that increases in RVR to sympathetic activation during passive heating are attenuated and return to that of normothermic baseline after cooling recovery. NEW & NOTEWORTHY Our data indicate that increases in renal vascular resistance to the cold pressor test (i.e., sympathetic activation) are attenuated during passive heating, but at the end of cooling recovery this response returns to that of normothermic baseline. Importantly, hemodynamic responses were assessed in arteries going to (renal artery) and within (segmental artery) the kidney, which has not been previously examined in the same study during thermal and/or sympathetic stressors.

scholarly journals High-fructose corn syrup-sweetened soft drink consumption increases vascular resistance in the kidneys at rest and during sympathetic activation

2020 ◽  
Vol 318 (4) ◽  
pp. F1053-F1065 ◽  
Author(s):  
Christopher L. Chapman ◽  
Tigran Grigoryan ◽  
Nicole T. Vargas ◽  
Emma L. Reed ◽  
Paul J. Kueck ◽  
...  
Keyword(s):  
Uric Acid ◽  
Vascular Resistance ◽  
Soft Drink ◽  
Cold Pressor Test ◽  
Cold Pressor ◽  
High Fructose Corn Syrup ◽  
Segmental Artery ◽  
Pressor Test ◽  
Caffeine Content ◽  
High Fructose

We first tested the hypothesis that consuming a high-fructose corn syrup (HFCS)-sweetened soft drink augments kidney vasoconstriction to sympathetic stimulation compared with water ( study 1). In a second study, we examined the mechanisms underlying these observations ( study 2). In study 1, 13 healthy adults completed a cold pressor test, a sympathoexcitatory maneuver, before (preconsumption) and 30 min after drinking 500 mL of decarbonated HFCS-sweetened soft drink or water (postconsumption). In study 2, venous blood samples were obtained in 12 healthy adults before and 30 min after consumption of 500 mL water or soft drinks matched for caffeine content and taste, which were either artificially sweetened (Diet trial), sucrose-sweetened (Sucrose trial), or sweetened with HFCS (HFCS trial). In both study 1 and study 2, vascular resistance was calculated as mean arterial pressure divided by blood velocity, which was measured via Doppler ultrasound in renal and segmental arteries. In study 1, HFCS consumption increased vascular resistance in the segmental artery at rest (by 0.5 ± 0.6 mmHg·cm−1·s−1, P = 0.01) and during the cold pressor test (average change: 0.5 ± 1.0 mmHg·cm−1·s−1, main effect: P = 0.05). In study 2, segmental artery vascular resistance increased in the HFCS trial (by 0.8 ± 0.7 mmHg·cm−1·s−1, P = 0.02) but not in the other trials. Increases in serum uric acid were greater in the HFCS trial (0.3 ± 0.4 mg/dL, P ≤ 0.04) compared with the Water and Diet trials, and serum copeptin increased in the HFCS trial (by 0.8 ± 1.0 pmol/L, P = 0.06). These findings indicate that HFCS acutely increases vascular resistance in the kidneys, independent of caffeine content and beverage osmolality, which likely occurs via simultaneous elevations in circulating uric acid and vasopressin.

Intracerebral vascular changes induced by cold pressor test: A model of sympathetic activation

1994 ◽  
Vol 16 (3) ◽  
pp. 163-167 ◽  
Author(s):  
Giuseppe Micieli ◽  
Cristina Tassorelli ◽  
Daniele Bosone ◽  
Anna Cavallini ◽  
Elena Viotti ◽  
...  
Keyword(s):  
Cold Pressor Test ◽  
Cold Pressor ◽  
Sympathetic Activation ◽  
Vascular Changes ◽  
Pressor Test

Inhibition by bradykinin of renal adrenergic effects in anesthetized rats

1984 ◽  
Vol 246 (4) ◽  
pp. F387-F394
Author(s):  
K. Inokuchi ◽  
K. U. Malik
Keyword(s):  
Arachidonic Acid ◽  
Renal Artery ◽  
Vascular Resistance ◽  
Nerve Stimulation ◽  
Rat Kidney ◽  
Renal Vascular Resistance ◽  
Cyclooxygenase Inhibitors ◽  
Renal Nerve ◽  
Anesthetized Rats ◽  
Renal Vascular

We studied the contribution of prostaglandins to the actions of bradykinin at the renal vascular adrenergic neuroeffector junction by examining the effect of the peptide on the decrease in renal blood flow elicited by renal nerve stimulation and injected norepinephrine in pentobarbital-anesthetized rats with or without pretreatment with the cyclooxygenase inhibitors sodium meclofenamate or indomethacin. Infusion of bradykinin, 10 ng X kg-1 X min-1, into the renal artery reduced both the basal and the rise in renal vascular resistance produced by nerve stimulation or norepinephrine. The prostaglandin precursor arachidonic acid, 5 micrograms X kg-1 X min-1, infused into the renal artery, also reduced renal vascular resistance and the vasoconstrictor response elicited by either adrenergic stimulus. In animals pretreated with either sodium meclofenamate or indomethacin, the effect of arachidonic acid, but not that of bradykinin, to produce renal vasodilation and to attenuate adrenergically induced renal vasoconstriction was abolished. These data suggest that bradykinin produces renal vasodilation and inhibits the renal vasoconstrictor effect of adrenergic stimuli in the rat kidney in vivo by a mechanism unrelated to prostaglandin synthesis.

Reliability and agreement of human renal and segmental artery hemodynamics measured using Doppler ultrasound

2020 ◽  
Vol 128 (3) ◽  
pp. 627-636 ◽  
Author(s):  
Christopher L. Chapman ◽  
Blair D. Johnson ◽  
David Hostler ◽  
Penelope C. Lema ◽  
Zachary J. Schlader
Keyword(s):  
Renal Artery ◽  
Doppler Ultrasound ◽  
Excellent Agreement ◽  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Data Interpretation ◽  
Blood Velocity ◽  
Current Standard ◽  
Segmental Artery ◽  
Segmental Arteries

To optimize study design and data interpretation, there is a need to understand the reliability of Doppler ultrasound-derived measures of blood velocity (BV) measured in the renal and segmental arteries. Thus, this study tested the following two hypotheses: 1) renal and segmental artery BV measured over the current standard of three cardiac cycles have good agreement with measurements over nine cardiac cycles ( study 1); and 2) renal and segmental artery BV measurements have relatively poor day-to-day reliability ( study 2). In study 1, there was excellent agreement between measurements over three and nine cardiac cycles for BV in both the renal and segmental arteries, as evidenced by BV measurements that were not statistically different ( P ≥ 0.68), were highly consistent ( r ≥ 0.99, P < 0.01), had a coefficient of variation ≤2.5 ± 1.8%, and 97% (renal artery) and 92% (segmental artery) of the individual differences fell within the 95% limits of agreement. In study 2, there was relatively good day-to-day reliability in renal artery BV as evidenced by no differences between three separate days ( P ≥ 0.30), an intraclass correlation coefficient (ICC) of 0.92 (0.78, 0.98), and 7.4 ± 5.5% coefficient of variation. The day-to-day reliability was relatively poor in the segmental artery with an ICC of 0.77 (0.41, 0.93) and 9.0 ± 5.6% coefficient of variation. These findings support measuring renal and segmental artery hemodynamics over three cardiac cycles and the utility in reporting renal BV across days. However, because of the variation across days, hemodynamic responses in the segmental arteries should be reported as changes from baseline when making comparisons across multiple days. NEW & NOTEWORTHY The present study indicates that Doppler ultrasound-derived measures of renal and segmental artery hemodynamics over three cardiac cycles have excellent agreement with those over nine cardiac cycles. These findings support the current practice of measuring renal and segmental artery blood velocity over three cardiac cycles. This study also demonstrates that there is excellent day-to-day reliability for measures of renal artery blood velocity, which supports reporting absolute values of renal artery blood velocity across days. However, it was also found that the day-to-day reliability of segmental artery measurements is relatively poor. Thus, to account for this variability, we suggest that segmental artery hemodynamics be compared as relative changes from baseline across separate days.

SYSTEMIC ADENOSINE INCREASE DURING COLD PRESSOR TEST IS DEPENDENT ON SYMPATHETIC ACTIVATION

1999 ◽  
Vol 26 (10) ◽  
pp. 774-778 ◽  
Author(s):  
FRANCO LAGHI Pasini ◽  
PIER LEOPOLDO Capecchi ◽  
MARCELLA Colafati ◽  
PAOLA Randisi ◽  
LUCA Puccetti
Keyword(s):  
Cold Pressor Test ◽  
Cold Pressor ◽  
Sympathetic Activation ◽  
Pressor Test

Cutaneous Vascular Responses Evoked in the Hand by the Cold Pressor Test and by Mental Arithmetic

1990 ◽  
Vol 79 (1) ◽  
pp. 43-50 ◽  
Author(s):  
I. Marriott ◽  
Janice M. Marshall ◽  
E. J. Johns
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Mental Arithmetic ◽  
Cold Pressor Test ◽  
Cold Pressor ◽  
Pressor Test ◽  
Contralateral Hand ◽  
The Right ◽  
Cutaneous Vascular Resistance

1. Laser Doppler flowmetry has been used to study changes in cutaneous erythrocyte flux produced in the hand (i) on successive immersion of the contralateral hand in water at 20°C (cold test) and then in water at 0–4°C (cold pressor test), and (ii) by mental arithmetic. 2. In 11 subjects, placing the right hand in water at 20°C for 2 min induced a significant decrease in cutaneous erythrocyte flux in the contralateral hand and a significant fall in mean arterial pressure. Cutaneous vascular resistance, calculated as arterial pressure/cutaneous erythrocyte flux, showed no significant change. Thus, the decrease in erythrocyte flux was apparently due to a fall in perfusion pressure. 3. Subsequent immersion of the right hand in water at 0–4°C for 2 min caused a significant decrease in erythrocyte flux in the contralateral hand and a significant rise in mean arterial pressure. It is concluded that the cold pressor response evoked from one hand elicited a substantial reflex vasoconstriction in the skin of the other hand; accordingly, calculated cutaneous vascular resistance increased significantly. 4. Eight subjects performed mental arithmetic for two periods of 2 min separated by a rest period of 2 min. By the end of the second minute of each period of mental arithmetic there was a significant decrease in erythrocyte flux. Mean arterial pressure increased significantly in the first period only, but calculated cutaneous vascular resistance increased in both periods, consistent with cutaneous vasoconstriction. 5. The cold pressor test and mental arithmetic are aversive stimuli that evoke the characteristic pattern of the alerting or defence response which includes splanchnic vasoconstriction and muscle vasodilatation. Previous studies on the cutaneous vascular component of this response have yielded equivocal results. The present study provides firm evidence that it includes cutaneous vasoconstriction, at least in the hand.

scholarly journals Mitigating Initial Orthostatic Hypotension: Mechanistic Roles of Muscle Contraction Versus Sympathetic Activation

Hypertension ◽  
2022 ◽  
Author(s):  
Nasia Sheikh ◽  
Aaron A. Phillips ◽  
Shaun Ranada ◽  
Matthew Lloyd ◽  
Karolina Kogut ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Electrical Stimulation ◽  
Mental Arithmetic ◽  
Stress Test ◽  
Cold Pressor Test ◽  
Cold Pressor ◽  
Sympathetic Activation ◽  
Pressor Test ◽  
Involuntary Muscle ◽  
Initial Orthostatic Hypotension

Background: Initial orthostatic hypotension (IOH) is defined by a large drop in blood pressure (BP) within 15 s of standing. IOH often presents during an active stand, but not with a passive tilt, suggesting that a muscle activation reflex involving lower body muscles plays an important role. To our knowledge, there is no literature exploring how sympathetic activation affects IOH. We hypothesized involuntary muscle contractions before standing would significantly reduce the drop in BP seen in IOH while increasing sympathetic activity would not. Methods: Study participants performed 4 sit-to-stand maneuvers including a mental stress test (serial 7 mental arithmetic stress test), cold pressor test, electrical stimulation, and no intervention. Continuous heart rate and beat-to-beat BP were measured. Cardiac output and systemic vascular resistance were estimated from these waveforms. Data are presented as mean±SD. Results: A total of 23 female IOH participants (31±8 years) completed the study. The drops in systolic BP following the serial 7 mental arithmetic stress test (−26±12 mm Hg; P =0.004), cold pressor test (−20±15 mm Hg; P <0.001), and electrical stimulation (−28±12 mm Hg; P =0.01) were significantly reduced compared with no intervention (−34±11 mm Hg). The drops in systemic vascular resistance following the serial 7 mental arithmetic stress test (−391±206 dyne×s/cm 5 ; P =0.006) and cold pressor test (−386±179 dyne×s/cm 5 ; P =0.011) were significantly reduced compared with no intervention (−488±173 dyne×s/cm 5 ). Cardiac output was significantly increased upon standing (7±2 L/min) compared with during the sit (6±1 L/min; P <0.001) for electrical stimulation. Conclusion: Sympathetic activation mitigates the BP response in IOH, while involuntary muscle contraction mitigates the BP response and reduces symptoms. Active muscle contractions may induce both of these mechanisms of action in their pretreatment of IOH. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03970551.

Acetylcholine chloride and renal hemodynamics during postnatal maturation in conscious lambs

1999 ◽  
Vol 87 (4) ◽  
pp. 1296-1300 ◽  
Author(s):  
Alp Sener ◽  
Francine G. Smith
Keyword(s):  
Renal Artery ◽  
Vascular Resistance ◽  
Renal Hemodynamics ◽  
Renal Vascular Resistance ◽  
Postnatal Maturation ◽  
Renal Vasoconstriction ◽  
Acetylcholine Chloride ◽  
Renal Vascular ◽  
Dose Dependent ◽  
Conscious Animals

To test the hypothesis that acetylcholine-induced relaxation of the renal artery decreases with postnatal age, we measured parameters of renal hemodynamics before and for 35 s after aortic suprarenal injection of acetylcholine in conscious, chronically instrumented lambs aged ∼1 wk ( n = 5) and ∼6 wk ( n = 5). Acetylcholine was administered in one of five doses ranging from 0 to 10 mg/kg body wt; doses were administered randomly, in the same volume. There were significant age- and dose-dependent changes in renal vascular resistance after acetylcholine administration, such that the response was greater in 1-wk-old lambs. After the highest dose tested, renal vascular resistance decreased by 13.6 ± 7.3 (SD) mmHg ⋅ ml−1 ⋅ min ⋅ g kidney wt in 1-wk-old lambs and by 9.1 ± 3.2 mmHg ⋅ ml−1 ⋅ min ⋅ g kidney wt in 6-wk-old lambs at 35 s. We also observed a transient renal vasoconstriction before the renal vasodilatation in 6-wk-old lambs but not in 1-wk-old animals. These data provide the first age- and dose-dependent effects of exogenous administration of acetylcholine on renal hemodynamics during maturation in conscious animals.

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