Vasopressin Secretion in Diabetic Subjects with and without Autonomic Neuropathy: Responses to Osmotic and Postural Stimulation

1989 ◽  
Vol 77 (6) ◽  
pp. 589-597 ◽  
Author(s):  
W. Reid ◽  
D. J. Ewing ◽  
S. L. Lightman ◽  
D. Eadington ◽  
T. D. M. Williams ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Body Weight ◽  
Autonomic Neuropathy ◽  
Plasma Osmolality ◽  
Normal Subjects ◽  
Cardiovascular Reflex ◽  
Head Up Tilt ◽  
Vasopressin Secretion ◽  
Osmotic Stimulus

1. The release of arginine vasopressin (AVP) after an osmotic stimulus and head-up tilt was assessed in diabetic subjects with and without autonomic neuropathy 2. Six diabetic subjects with (DAN +ve) and five without (DAN − ve) evidence of autonomic neuropathy and five normal subjects were infused with 5% (w/v) NaCl at a rate of 0.05 ml min−1 kg−1 body weight for 120 min. Blood pressure, heart rate and plasma AVP were measured over this period 3. Seven DAN +ve, six DAN −ve and six normal subjects were tilted head-up to 45° for 120 min. Blood pressure, heart rate and plasma AVP were measured during the study 4. Infusion of 5% (w/v) NaCl produced appropriate rises in plasma osmolality and plasma AVP levels which did not differ between the three groups, confirming the normal osmotic release of AVP in the diabetic subjects 5. During head-up tilt, there were no differences in AVP responses between the three groups, despite a major hypotensive stimulus in the DAN + ve group 6. We conclude that osmotic release of AVP is normal in diabetes, but that cardiovascular release of AVP is impaired in diabetic subjects with cardiovascular reflex evidence of autonomic neuropathy, reflecting an afferent defect.

Effects of Oral Alcohol on Superior Mesenteric Artery Blood Flow in Normal Man, Horizontal and Tilted

1993 ◽  
Vol 84 (4) ◽  
pp. 419-425 ◽  
Author(s):  
S. Maule ◽  
K. Ray Chaudhuri ◽  
T. Thomaides ◽  
D. Pavitt ◽  
J. McCleery ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Body Weight ◽  
Cardiac Index ◽  
Superior Mesenteric Artery ◽  
Mesenteric Artery ◽  
Cardiovascular Effects ◽  
Normal Subjects ◽  
Head Up Tilt

1. The cardiovascular effects of oral alcohol (0.5 g/kg body weight diluted to 300 ml in sugar-free orange juice) were compared with those of placebo in 10 normal subjects. Measurements were made while the subjects were supine and horizontal for 45 min and after 10 min of 45° head-up tilt. 2. After alcohol, plasma alcohol levels rose from 1.9 ± 1.3 to 61.6 ± 6.5 mg/100 ml. After placebo, plasma alcohol levels did not increase. After alcohol and placebo, supine blood pressure was unchanged; heart rate, both supine and during tilt, rose after alcohol only. 3. After alcohol, superior mesenteric artery and digital skin blood flow increased and calculated vascular resistances fell. There was no change after placebo. 4. Forearm blood flow, forearm vascular resistance and cardiac index did not change in either phase, except for a fall in cardiac index during tilt but only after alcohol. 5. In conclusion, the acute ingestion of 0.5 g of alcohol/kg body weight in normal subjects raised heart rate and actively dilated the superior mesenteric artery and digital skin vessels. There was no effect on blood pressure, cardiac output and skeletal muscle vascular tone. During head-up tilt after alcohol, there was a tendency for blood pressure to fall with a compensatory rise in heart rate.

Carotid arterial haemodynamics after mild degrees of lower-body negative pressure in man

1992 ◽  
Vol 83 (5) ◽  
pp. 535-540 ◽  
Author(s):  
P. J. Lacolley ◽  
B. M. Pannier ◽  
M. A. Slama ◽  
J. L. Cuche ◽  
A. P. G. Hoeks ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Weight Bearing ◽  
Normal Subjects ◽  
Lower Body ◽  
Head Up Tilt ◽  
Cardiopulmonary Receptors ◽  
Carotid Arterial

1. Pulsatile changes in the diameter of the common carotid artery were studied transcutaneously using an echo-tracking technique in 15 normal subjects: eight subjects before and during application of graded lower-body negative pressure from −5 to −15 mmHg, and seven subjects before and during weight-bearing head-up tilt at 30 and 60 degrees. 2. In concomitant studies of changes in forearm vascular resistance, it was seen that mild lower-body negative pressure produced deactivation of cardiopulmonary receptors without changes in systemic blood pressure or heart rate. 3. After lower-body negative pressure, a significant decrease in carotid arterial diastolic diameter [from 0.662 ± 0.028 to 0.624 ± 0.033 cm (lower-body negative pressure −10 mmHg) and 0.640 ± 0.030 cm lower-body negative pressure −15 mmHg), P<0.001 and <0.05] was observed. 4. After head-up tilt, carotid arterial diameter was also significantly decreased at 30 and 60 degrees, whereas a significant increase in heart rate occurred only at 60 degrees and mean blood pressure did not change. 5. The study provides evidence that the geometry of the arterial wall is substantially modified by noninvasive manoeuvres such as head-up tilting and lower-body negative pressure. The latter is assumed to selectively deactivate human cardiopulmonary receptors, but the present data suggest that local changes may also influence carotid baroreceptors.

Afferent baroreflex dysfunction and age-related orthostatic hypotension

1991 ◽  
Vol 81 (s25) ◽  
pp. 531-538 ◽  
Author(s):  
A. L. Tonkin ◽  
L. M. H. Wing ◽  
M. J. Morris ◽  
V. Kapoor
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cold Stress ◽  
Orthostatic Hypotension ◽  
Autonomic Neuropathy ◽  
Isometric Exercise ◽  
Control Subjects ◽  
Age Related ◽  
Head Up Tilt ◽  
Elderly Control

1. To test the hypothesis that in apparently healthy elderly subjects with orthostatic hypotension there is afferent baroreflex dysfunction, cardiovascular and neurohumoral responses were measured after separate stimuli which activated baroreceptor (head-up tilt) and non-baroreceptor (cold stress, isometric exercise) afferent pathways. 2. In 15 healthy elderly control subjects blood pressure did not change with 60° head-up tilting and there was a moderate increase in heart rate, whereas in 13 subjects with age-related orthostatic hypotension head-up tilting was associated with a marked fall in blood pressure but a similar heart rate response to that in the elderly control group. In contrast, both groups of subjects had similar blood pressure and heart rate responses to cold stress and sustained isometric exercise. 3. Nine subjects with autonomic neuropathy also showed a marked hypotensive response to head-up tilt, but produced no pressor response to cold stress or isometric exercise. 4. The plasma concentrations of noradrenaline, adrenaline and neuropeptide-Y-like immunoreactivity rose and that of atrial natriuretic peptide fell after head-up tilt in the study population as a whole. There were no significant differences between groups despite the much greater blood pressure drops in the subjects with autonomic neuropathy and in those with age-associated orthostatic hypotension. 5. The aorto-iliac pulse wave velocity index was significantly higher in subjects with age-associated orthostatic hypotension compared with that in control subjects. 6. The pattern of responses to the separate stresses observed in the group with age-associated orthostatic hypotension is characteristic and different from that in the elderly control subjects and the subjects with autonomic neuropathy. It suggests that age-associated orthostatic hypotension is related predominantly to dysfunction in the afferent limb of the baroreflex arc, possibly partially caused by a splinting of arterial baroreceptors by non-compliant arterial walls.

Endogenous Opioids Modulate Central Nervous System Blood Pressure Control in Man

1982 ◽  
Vol 63 (s8) ◽  
pp. 331s-333s ◽  
Author(s):  
P. C. Rubin ◽  
Kathleen McLean ◽  
J. L. Reid
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Pressure Control ◽  
Normal Subjects ◽  
Pressure Control ◽  
Endogenous Opioids ◽  
Plasma Noradrenaline ◽  
Head Up Tilt ◽  
Blind Manner

1. Two studies were performed to elucidate the role of opioids in blood pressure control in man. 2. Study 1: nine normal subjects, 18–32 years, received in a randomized single blind manner, volume matched infusions of a Met-enkephalin analogue (DAMME) 0.5 mg, naloxone 0.2 mg/kg or saline. Blood pressure, heart rate and plasma noradrenaline were determined supine and after a 5 min, 70° head-up tilt at 0, 3/4, 2, 3, 4, 5 and 6 h. 3. Study 2: seven subjects, after baseline recordings of blood pressure and heart rate received six incremental infusions of sodium nitroprusside, 1.5–7.5 μg min−1 kg−1. They then received DAMME or naloxone and the nitroprusside infusions were repeated between 3 and 4 h. There was a significant linear relationship between fall in mean arterial pressure and rise in heart rate in each case and the slope was used as an index of baroreflex sensitivity. 4. Neither naloxone nor DAMME influenced supine blood pressure or heart rate. Blood pressure after head-up tilt was significantly (analysis of variance) decreased by DAMME for up to 5 h but not by naloxone, the effect being most marked at 3 h: systolic (mean ± sd), placebo 110 ± 6, naloxone 106 ± 10, DAMME 96 ± 16 (P< 0.02); diastolic (mean ± sd), placebo 78 ± 7, naloxone 79 ± 5, DAMME 67 ± 8 (P < 0.01). The increases in heart rate and plasma noradrenaline on tilting after DAMME were not significantly different from values with placebo or naloxone. The 3 h values for heart rate were: placebo 87 ± 16, naloxone 88 ± 19, DAMME 89 ± 23 (P > 0.1); for plasma noradrenaline (nmol/l): placebo 6.0 ± 2.2, naloxone 5.8 ± 1.9, DAMME 6.0 ± 1.9 (P > 0.1). 5. Naloxone significantly increased the slope (beats per min/mmHg) of the regression relationship from a mean of 1.8 ± 0.07 to 3.0 ± 1.3 (P < 0.05), and DAMME reduced the slope from 2.7 ± 1.7 to 1.2 ± 0.5 (P < 0.05). 6. We conclude that endogenous opioids modulate baroreflex function in man.

Heart rate and blood pressure variabilities during graded head-up tilt

1995 ◽  
Vol 78 (1) ◽  
pp. 212-216 ◽  
Author(s):  
S. Mukai ◽  
J. Hayano
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Tilt Angle ◽  
High Frequency ◽  
Low Frequency ◽  
Normal Subjects ◽  
Arterial Baroreflex ◽  
Frequency Components ◽  
Head Up Tilt ◽  
High Level

We investigated the responses of the frequency components of heart rate (HR) and blood pressure (BP) variabilities to progressive changes in autonomic activity induced by the graded head-up tilt technique in 12 normal subjects (age 19–27 yr) under the condition of frequency-controlled respiration (0.25 Hz). During low-level tilt (0–30 degrees), the R-R interval was unchanged and the amplitude of the high-frequency (HF; 0.25 Hz) component of HR variability showed only a slight insignificant decrease. The amplitude of the low-frequency (LF; 0.04–0.15 Hz) component of HR variability increased progressively as the angle increased (P < 0.05). During high-level tilt (30–90 degrees), the R-R interval and the HF amplitude of HR variability decreased progressively with tilt angle (P < 0.001 for both). The LF amplitude of HR variability peaked at a tilt angle of 30 degrees. The LF-to-HF ratio of HR variability and the LF amplitude of systolic and diastolic BP variabilities increased progressively as the tilt angle increased from 0 to 60 degrees (P < 0.001), although systolic and diastolic BPs were unchanged. These results suggest that mixed autonomic responses to orthostatic stress, which are thought to be mediated by both cardiopulmonary and arterial baroreflex mechanisms, can be distinguished by changes in the frequency components of HR and BP variabilities.

scholarly journals Sympathetic neural and hemodynamic responses to head-up tilt during isoosmotic and hyperosmotic hypovolemia

2017 ◽  
Vol 118 (4) ◽  
pp. 2232-2237 ◽  
Author(s):  
Alexander M. Posch ◽  
Adam J. Luippold ◽  
Katherine M. Mitchell ◽  
Karleigh E. Bradbury ◽  
Robert W. Kenefick ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Body Weight ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Nerve Activity ◽  
Main Effect ◽  
Head Up Tilt ◽  
Per Se ◽  
Exercise Induced

We hypothesized that muscle sympathetic nerve activity (MSNA) during head-up tilt (HUT) would be augmented during exercise-induced (hyperosmotic) dehydration but not isoosmotic dehydration via an oral diuretic. We studied 26 young healthy subjects (7 female, 19 male) divided into three groups: euhydrated (EUH, n = 7), previously exercised in 40°C while maintaining hydration; dehydrated (DEH, n = 10), previously exercised in 40°C during which ~3% of body weight was lost via sweat loss; and diuretic (DIUR, n = 9), a group that did not exercise but lost ~3% of body weight via diuresis (furosemide, 80 mg by mouth). We measured MSNA, heart rate (HR), and blood pressure (BP) during supine rest and 30° and 45° HUT. Plasma volume (PV) decreased similarly in DEH (−8.5 ± 3.3%) and DIUR (−11.4 ± 5.7%) ( P > 0.05). Plasma osmolality was similar between DIUR and EUH (288 ± 4 vs. 284 ± 5 mmol/kg, respectively) but was significantly higher in DEH (299 ± 5 mmol/kg) ( P < 0.05). Mixed-model ANOVA was used with repeated measures on position (HUT) and between-group analysis on condition. HR and MSNA increased in all subjects during HUT (main effect of position; P < 0.05). There was also a significant main effect of group, such that MSNA and HR were higher in DEH compared with DIUR ( P < 0.05). Changes in HR with HUT were larger in both hypovolemic groups compared with EUH ( P < 0.05). The differential HUT response “strategies” in each group suggest a greater role for hypovolemia per se in controlling HR responses during dehydration, and a stronger role for osmolality in control of SNA. NEW & NOTEWORTHY Interactions of volume regulation with control of vascular sympathetic nerve activity (SNA) have important implications for blood pressure regulation. Here, we demonstrate that SNA and heart rate (HR) during hyperosmotic hypovolemia (exercise-induced) were augmented during supine and tilt compared with isoosmotic hypovolemia (diuretic), which primarily augmented the HR response. Our data suggest that hypovolemia per se had a larger role in controlling HR responses, whereas osmolality had a stronger role in control of SNA.

Effects of body weight-supported treadmill training on heart rate variability and blood pressure variability in individuals with spinal cord injury

2005 ◽  
Vol 98 (4) ◽  
pp. 1519-1525 ◽  
Author(s):  
David S. Ditor ◽  
Mark V. Kamath ◽  
Maureen J. MacDonald ◽  
Joanne Bugaresti ◽  
Neil McCartney ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Heart Rate ◽  
Spinal Cord Injury ◽  
Body Weight ◽  
Autonomic Regulation ◽  
Treadmill Training ◽  
Increased Risk ◽  
Cord Injury ◽  
Head Up Tilt

Individuals with spinal cord injury are prone to cardiovascular dysfunction and an increased risk of cardiovascular disease. Body weight-supported treadmill training (BWSTT) may enhance ambulation in individuals with incomplete spinal cord injury; however, its effects on cardiovascular regulation have not been investigated. The purpose of this study was to examine the effects of 6-mo of BWSTT on the autonomic regulation of heart rate (HR) and blood pressure (BP) in individuals with incomplete tetraplegia. Eight individuals [age 27.6 yr (SD 5.2)] with spinal cord injury [C4–C5; American Spinal Injury Association B-C; 9.6 yr (SD 7.5) postinjury] participated. Ten-minute HR and finger arterial pressure (Finapres) recordings were collected during 1) supine rest and 2) an orthostatic stress (60° head-up tilt) before and after 6 mo of BWSTT. Frequency domain measures of HR variability [low-frequency (LF) power, high-frequency (HF) power, and LF-to-HF ratio] and BP variability (systolic and diastolic LF power) were used as clinically valuable indexes of neurocardiac and neurovascular control, respectively. There was a significant reduction in HR [61.9 (SD 6.9) vs. 55.7 beats/min (SD 7.7); P = 0.05] and LF-to-HF ratio [1.23 (SD 0.47) vs. 0.99 (SD 0.40); P < 0.05] after BWSTT. There was a significant reduction in LF systolic BP [183.1 (SD 46.8) vs. 158.4 mmHg2 (SD 45.2); P < 0.01] but no change in BP. There were no significant effects of training on HR variability or BP variability during 60° head-up tilt. In conclusion, individuals with incomplete tetraplegia retain the ability to make positive changes in cardiovascular autonomic regulation with BWSTT without worsening orthostatic intolerance.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

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