Aging, opioid-receptor agonists and antagonists, and the vestibulosympathetic reflex in humans

2004 ◽  
Vol 96 (5) ◽  
pp. 1761-1766 ◽  
Author(s):  
Chester A. Ray ◽  
Kevin D. Monahan
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Opioid Receptor ◽  
Muscle Sympathetic Nerve Activity ◽  
Endogenous Opioids ◽  
Arterial Blood ◽  
Before And After ◽  
Vestibulosympathetic Reflex ◽  
Older Subjects

Animal studies indicate that opioids inhibit the firing rate of vestibular neurons, which are important in mediating the vestibulosympathetic reflex. Furthermore, this inhibition appears to be greater in more mature rats. In the present study, we tested the hypotheses that opioids inhibit the vestibulosympathetic reflex in humans and that endogenous opioids contribute to the age-related impairment of the vestibulosympathetic reflex. These hypotheses were tested by measuring muscle sympathetic nerve activity (MSNA), arterial blood pressure, and heart rate responses to otolith organ engagement during head-down rotation (HDR) in young (24 ± 2 yr old) and older (63 ± 2 yr) subjects before and after administration of either an opioid-receptor antagonist (16 mg naloxone in 9 young and 8 older subjects) or an opioid-receptor agonist (60 mg codeine in 7 young and 7 older subjects). Naloxone did not augment the reflex increase in MSNA during HDR in young (Δ7 ± 2 vs. Δ4 ± 2 bursts/min and Δ81 ± 23 vs. Δ60 ± 24% change in burst frequency and total MSNA before and after naloxone, respectively) or older subjects (Δ2 ± 2 vs. Δ1 ± 2 burst/min and Δ8 ± 7 vs. Δ8 ± 9% before and after naloxone). Similarly, codeine did not attenuate the increase in MSNA during HDR in young (Δ8 ± 1 vs. Δ7 ± 2 bursts/min and Δ53 ± 4 vs. Δ64 ± 16% before and after codeine) or older subjects (Δ6 ± 4 vs. Δ3 ± 3 bursts/min and Δ38 ± 21 vs. Δ33 ± 20%). Mean arterial blood pressure and heart rate responses to HDR were not altered by either naloxone or codeine. These data do not provide experimental support for the concept that opioids modulate the vestibulosympathetic reflex in humans. Moreover, endogenous opioids do not appear to contribute the age-associated impairment of the vestibulosympathetic reflex.

scholarly journals Is there diurnal variation of the vestibulosympathetic reflex: implications for orthostatic hypotension

2013 ◽  
Vol 305 (10) ◽  
pp. H1555-H1559
Author(s):  
Chester A. Ray ◽  
Charity L. Sauder ◽  
Stephanie A. Chin-Sang ◽  
Jonathan S. Cook
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Diurnal Variation ◽  
Orthostatic Hypotension ◽  
Arterial Blood Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Blood ◽  
Calf Blood Flow ◽  
Vestibulosympathetic Reflex

Incidences of adverse cardiac events and orthostatic hypotension are associated with diurnal variations. The primary purpose of the present study was to determine if the vestibulosympathetic reflex (VSR) follows a diurnal variation in humans. We hypothesized that the VSR would be attenuated at night based on the relation between melatonin and the VSR. Arterial blood pressure, heart rate, calf blood flow, and muscle sympathetic nerve activity (MSNA) were measured in nine healthy subjects (28 ± 1 yr, 5 men and 4 women) at rest and during head-down rotation. Each subject was tested during the day at 11:34 ± 13 and again at night 22:10 ± 5. MSNA was significantly decreased at night compared with day (8 ± 1 vs. 11 ± 2 bursts/min, respectively, P < 0.02). Heart rate and arterial blood pressure at rest were significantly increased at night compared with day (heart rate: 70 ± 4 vs. 66 ± 4 beats/min and mean arterial blood pressure: 91 ± 2 vs. 87 ± 1 mmHg, respectively). MSNA and hemodynamic responses to head-down rotation were not significantly altered at night compared with day (changes of 3 ± 1 bursts/min and 25 ± 6% for MSNA and calf blood flow, respectively). The data indicate that MSNA at rest decreases during the late evening hours and exhibits a diurnal variation, whereas the VSR does not. In summary, diurnal variation of orthostatic hypotension in humans does not appear to be associated with changes in the VSR and MSNA at rest.

Baroreflex control of muscle sympathetic nerve activity during skin surface cooling

2007 ◽  
Vol 103 (4) ◽  
pp. 1284-1289 ◽  
Author(s):  
Jian Cui ◽  
Sylvain Durand ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Skin Surface ◽  
Surface Cooling ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Arterial Blood

Skin surface cooling improves orthostatic tolerance through a yet to be identified mechanism. One possibility is that skin surface cooling increases the gain of baroreflex control of efferent responses contributing to the maintenance of blood pressure. To test this hypothesis, muscle sympathetic nerve activity (MSNA), arterial blood pressure, and heart rate were recorded in nine healthy subjects during both normothermic and skin surface cooling conditions, while baroreflex control of MSNA and heart rate were assessed during rapid pharmacologically induced changes in arterial blood pressure. Skin surface cooling decreased mean skin temperature (34.9 ± 0.2 to 29.8 ± 0.6°C; P < 0.001) and increased mean arterial blood pressure (85 ± 2 to 93 ± 3 mmHg; P < 0.001) without changing MSNA ( P = 0.47) or heart rate ( P = 0.21). The slope of the relationship between MSNA and diastolic blood pressure during skin surface cooling (−3.54 ± 0.29 units·beat−1·mmHg−1) was not significantly different from normothermic conditions (−2.94 ± 0.21 units·beat−1·mmHg−1; P = 0.19). The slope depicting baroreflex control of heart rate was also not altered by skin surface cooling. However, skin surface cooling shifted the “operating point” of both baroreflex curves to high arterial blood pressures (i.e., rightward shift). Resetting baroreflex curves to higher pressure might contribute to the elevations in orthostatic tolerance associated with skin surface cooling.

Heart rate and blood pressure effects during caloric vestibular testing

2010 ◽  
Vol 124 (6) ◽  
pp. 616-622 ◽  
Author(s):  
A V Kasbekar ◽  
D M Baguley ◽  
R Knight ◽  
P Gomersall ◽  
R Parker ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Phase Velocity ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Pressure Effects ◽  
Slow Phase ◽  
Slow Phase Velocity ◽  
Arterial Blood ◽  
Before And After

AbstractObjectives:To determine whether the caloric vestibular test causes significant changes in heart rate and mean arterial blood pressure.Materials and methods:Changes in heart rate and mean arterial blood pressure before and after caloric irrigation were compared with the degree of nystagmus (as measured by maximum slow phase velocity) and the patient's subjective dizziness (scored from 0 to 10). A cardiologist reviewed each patient's heart rate and mean arterial blood pressure changes. Patients' anxiety levels were also assessed.Results:Eighteen patients were recruited. There were no adverse events in any patient. There were no overall significant differences between the heart rate and mean arterial pressure before and after each irrigation. There was a significant correlation between the maximum slow phase velocity and patients' subjective dizziness scores.Conclusion:Heart rate and mean arterial blood pressure are not significantly influenced by the caloric vestibular test. This preliminary study will enable patients with stable cardiovascular disease to be recruited for further risk determination.

Systemic Haemodynamics in Mild Arterial Hypertension before and after Physical Training

1973 ◽  
Vol 45 (s1) ◽  
pp. 145s-149s ◽  
Author(s):  
R. Sannerstedt ◽  
H. Wasir ◽  
R. Henning ◽  
L. Werkö
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Hypertension ◽  
Arterial Blood Pressure ◽  
Physical Training ◽  
Blood Pressure Level ◽  
Work Load ◽  
Physical Conditioning ◽  
Arterial Blood ◽  
Before And After

1. Five men with borderline, latent arterial hypertension of the hyperkinetic type were studied haemodynamically at rest and during dynamic exercise before and after a 6-week period of supervised physical training. 2. Tendencies to lower heart rate, cardiac output and arterial blood pressure, both at rest and during a standardized work-load, were observed after the training period, with significant differences between paired observations for the heart rate and mean arterial blood pressure during exercise. The systemic vascular resistance being unchanged, there was a certain trend to an increased widening of the arteriovenous oxygen difference, both at rest and during exercise. 3. The present findings from a small number of subjects indicate that physical conditioning of patients with latent hypertension of the hyperkinetic type contributes to a normalization of their circulation toward a normokinetic one, thereby also normalizing their blood pressure level and achieving a more economic energy expenditure in the cardiovascular system.

scholarly journals Comparison of intraocular pressure, tear production and cardiorespiratory variables before and after induction of anaesthesia with either propofol or ketofol in dogs premedicated with midazolam

2018 ◽  
Vol 63 (No. 6) ◽  
pp. 271-278
Author(s):  
H. Imani Rastabi ◽  
A. Baniadam ◽  
A. Ronagh ◽  
A. Khajeh ◽  
M. Kamyabnia
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Intraocular Pressure ◽  
Respiratory Depression ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Arterial Blood ◽  
Tear Production ◽  
Before And After ◽  
Induction Of Anaesthesia

The objective of the present study was to compare the effects of propofol and ketofol on intraocular pressure, tear production and cardiorespiratory variables in dogs premedicated with midazolam. Six castrated adult mixed-breed dogs were used in a cross-over design with a one-week interval. Twenty minutes after premedication with midazolam (0.2 mg/kg), animals were assigned randomly to two groups and received either propofol (6 mg/kg) or ketofol (3 mg/kg; 1 : 1 mg/ml ratio) treatments intravenously. Intraocular pressure, tear production, heart rate, respiratory rate, rectal temperature and direct mean arterial blood pressure were measured at base (before induction), and at 5, 10, 15, 20 and 30 min after induction of anaesthesia. Blood gas samples were obtained at base (before induction), and at 5, 15 and 30 min after administration of treatments. Intraocular pressure showed significantly higher values at 5 min after induction in ketofol compared with propofol (16.1 ± 4.5 mm Hg vs 8.2 ± 1.2 mm Hg, respectively). There were no significant changes in tear production in either group. Significantly higher heart rate and mean arterial blood pressure were detected in ketofol at several time points. Respiratory depression occurred in both groups with no significant differences between them. In conclusion, although ketofol improved heart rate and mean arterial blood pressure and did not elicit more pronounced respiratory depression than propofol, it resulted in significantly higher values of intraocular pressure at 5 min after administration in dogs. Despite the small number of dogs in this study, our results indicate that ketofol should not be recommended for ophthalmic surgical procedures in dogs. Appropriate oxygenation should be provided when propofol is used for ophthalmic surgeries.

Vestibulosympathetic reflex during orthostatic challenge in aging humans

2002 ◽  
Vol 283 (5) ◽  
pp. R1027-R1032 ◽  
Author(s):  
Kevin D. Monahan ◽  
Chester A. Ray
Keyword(s):  
Blood Pressure ◽  
Older Adults ◽  
Arterial Blood Pressure ◽  
Orthostatic Stress ◽  
Pressure Regulation ◽  
Orthostatic Challenge ◽  
Arterial Blood ◽  
Age Related ◽  
Vestibulosympathetic Reflex ◽  
Older Subjects

Aging attenuates the increase in muscle sympathetic nerve activity (MSNA) and elicits hypotension during otolith organ engagement in humans. The purpose of the present study was to determine the neural and cardiovascular responses to otolithic engagement during orthostatic stress in older adults. We hypothesized that age-related impairments in the vestibulosympathetic reflex would persist during orthostatic challenge in older subjects and might compromise arterial blood pressure regulation. MSNA, arterial blood pressure, and heart rate responses to head-down rotation (HDR) performed with and without lower body negative pressure (LBNP) in prone subjects were measured. Ten young (27 ± 1 yr) and 11 older subjects (64 ± 1 yr) were studied prospectively. HDR performed alone elicited an attenuated increase in MSNA in older subjects (Δ106 ± 28 vs. Δ20 ± 7% for young and older subjects). HDR performed during simultaneous orthostatic stress increased total MSNA further in young (Δ53 ± 15%; P < 0.05) but not older subjects (Δ−5 ± 4%). Older subjects demonstrated consistent significant hypotension during HDR performed both alone (Δ−6 ± 2 mmHg) and during LBNP (Δ−7 ± 2 mmHg). These data provide experimental support for the concept that age-related impairments in the vestibulosympathetic reflex persist during orthostatic challenge in older adults. Furthermore, these findings are consistent with the concept that age-related alterations in vestibular function might contribute to altered orthostatic blood pressure regulation with age in humans.

Phenylephrine-induced elevations in arterial blood pressure are attenuated in heat-stressed humans

2002 ◽  
Vol 283 (5) ◽  
pp. R1221-R1226 ◽  
Author(s):  
Jian Cui ◽  
Thad E. Wilson ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Arterial Blood Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Peripheral Resistance ◽  
Whole Body ◽  
Baroreflex Control ◽  
Arterial Blood ◽  
The Relationship

To test the hypothesis that phenylephrine-induced elevations in blood pressure are attenuated in heat-stressed humans, blood pressure was elevated via steady-state infusion of three doses of phenylephrine HCl in 10 healthy subjects in both normothermic and heat stress conditions. Whole body heating significantly increased sublingual temperature by ∼0.5°C, muscle sympathetic nerve activity (MSNA), heart rate, and cardiac output and decreased total peripheral vascular resistance (TPR; all P < 0.005) but did not change mean arterial blood pressure (MAP; P > 0.05). At the highest dose of phenylephrine, the increase in MAP and TPR from predrug baselines was significantly attenuated during the heat stress [ΔMAP 8.4 ± 1.2 mmHg; ΔTPR 0.96 ± 0.85 peripheral resistance units (PRU)] compared with normothermia (ΔMAP 15.4 ± 1.4 mmHg, ΔTPR 7.13 ± 1.18 PRU; all P < 0.001). The sensitivity of baroreflex control of MSNA and heart rate, expressed as the slope of the relationship between MSNA and diastolic blood pressure, as well as the slope of the relationship between heart rate and systolic blood pressure, respectively, was similar between thermal conditions (each P > 0.05). These data suggest that phenylephrine-induced elevations in MAP are attenuated in heat-stressed humans without affecting baroreflex control of MSNA or heart rate.

Acute Haemodynamic and Hormonal Effects of Captopril are Diminished by Indomethacin

1982 ◽  
Vol 62 (6) ◽  
pp. 611-615 ◽  
Author(s):  
H. Witzgall ◽  
F. Hirsch ◽  
B. Scherer ◽  
P. C. Weber
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Plasma Renin ◽  
Hormonal Effects ◽  
Arterial Blood ◽  
Before And After ◽  
Pre Treatment ◽  
Excretion Rates

1. The acute haemodynamic and hormonal effects of 100 mg of captopril (SQ 14.225) orally were tested in twelve healthy men in the sodium replete state before and after indomethacin pre-treatment. 2. Without indomethacin, mean arterial blood pressure was reduced at 30 and 60 min after captopril (P < 0.02). Heart rate did not change during the whole experiment. Although plasma renin activity (PRA) increased (P < 0.002), plasma and urinary aldosterone and plasma 18-hydroxycorticosterone (18-OH-B) decreased after captopril (P < 0.02). Prostaglandin (PG) E2, sodium and potassium excretion rates remained constant after captopril. 3. Under indomethacin pretreatment, the fall in mean arterial blood pressure was less than without indomethacin at 30 and 60 min after captopril (P < 0.05). Heart rate was constantly lower than without indomethacin during the whole experiment (P < 0.05). Indomethacin pretreatment decreased basal PGE2 excretion (P < 0.02) and baseline PRA as well as the increase in PRA after captopril (P < 0.05). Control mineralocorticoid levels were significantly lower than without indomethacin. In indomethacin-pretreated subjects, aldosterone did not further decrease after captopril, and 18-OH-B fell only slightly. 4. Without indomethacin pretreatment a significant, positive correlation was found between PRA values before captopril and the maximum decrease of mean arterial blood pressure after captopril. Under indomethacin pretreatment this correlation was no longer demonstrable. The results suggest that prostaglandins may contribute to the haemodynamic and hormonal actions of captopril.

Sympathetic vascular transduction is augmented in young normotensive blacks

2002 ◽  
Vol 92 (2) ◽  
pp. 651-656 ◽  
Author(s):  
Chester A. Ray ◽  
Kevin D. Monahan
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Vascular Resistance ◽  
Forearm Blood Flow ◽  
Lower Body Negative Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Blood ◽  
Blacks And Whites

The purpose of the present study was to determine sympathetic vascular transduction in young normotensive black and white adults. We hypothesized that blacks would demonstrate augmented transduction of muscle sympathetic nerve activity (MSNA) into vascular resistance. To test this hypothesis, MSNA, forearm blood flow, heart rate, and arterial blood pressure were measured during lower body negative pressure (LBNP). At rest, no differences existed in arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance (FVR). Likewise, LBNP elicited comparable responses of these variables for blacks and whites. Baseline MSNA did not differ between blacks and whites, but whites demonstrated greater increases during LBNP (28 ± 7 vs. 55 ± 18%, 81 ± 21 vs. 137 ± 42%, 174 ± 81 vs. 556 ± 98% for −5, −15, and −40 mmHg LBNP, respectively; P < 0.001). Consistent with smaller increases in MSNA but similar FVR responses during LBNP, blacks demonstrated greater sympathetic vascular transduction (%FVR/%MSNA) than whites (0.95 ± 0.07 vs. 0.82 ± 0.07 U; 0.82 ± 0.11 vs. 0.64 ± 0.09 U; 0.95 ± 0.37 vs. 0.35 ± 0.09 U; P < 0.01). In summary, young whites demonstrate greater increases in MSNA during baroreceptor unloading than age-matched normotensive blacks. However, more importantly, for a given increase in MSNA, blacks demonstrate greater forearm vasoconstriction than whites. This finding may contribute to augmented blood pressure reactivity in blacks.

Compression Stocking Length Effects on Arterial Blood Pressure and Heart Rate Following Head-Up Tilt in Healthy Volunteers

2014 ◽  
Vol 63 (6) ◽  
pp. 435-438 ◽  
Author(s):  
Kunihiko Tanaka ◽  
Shiori Tokumiya ◽  
Yumiko Ishihara ◽  
Yumiko Kohira ◽  
Tetsuro Katafuchi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Healthy Volunteers ◽  
Arterial Blood Pressure ◽  
Compression Stocking ◽  
Arterial Blood ◽  
Head Up Tilt ◽  
Length Effects
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