The Influence of Acute Starvation on the Cardiovascular Responses to Lower Body Subatmospheric Pressure or to Standing in Man

1984 ◽  
Vol 66 (2) ◽  
pp. 141-146 ◽  
Author(s):  
T. Bennett ◽  
I. A. MacDonald ◽  
R. Sainsbury
Keyword(s):  
Blood Pressure ◽  
Nervous Activity ◽  
Cardiovascular Responses ◽  
Sympathetic Nervous Activity ◽  
Normal Male ◽  
Lower Body ◽  
Subatmospheric Pressure ◽  
Acute Starvation ◽  
Male Subjects ◽  
Forearm Vascular Resistance

1. The cardiovascular responses to lower body subatmospheric pressure or to standing were measured in the same nine normal male subjects after a 12 h and after a 48 h fast. 2. After the 48 h fast there was a significant reduction in diastolic blood pressure and forearm vascular resistance (relative to the values after a 12 h fast) when subjects were supine. 3. During exposure to lower body subatmospheric pressure, subjects who had fasted for 48 h showed an inability to maintain systolic blood pressure, accompanied by an impairment of forearm vasoconstriction and an exaggerated tachycardia (relative to their responses after a 12 h fast). Similar disorders of cardiovascular homoeostasis were seen on standing. 4. The results are consistent with an inhibition of sympathetic nervous activity after a 48 h fast, but other possibilities are discussed.

Increase in Prostaglandins during Converting Enzyme Inhibition

1980 ◽  
Vol 59 (s6) ◽  
pp. 133s-135s ◽  
Author(s):  
S. L. Swartz ◽  
G. H. Williams ◽  
N. K. Hollenberg ◽  
F. R. Crantz ◽  
L. Levine ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Plasma Concentration ◽  
Sodium Intake ◽  
Thromboxane A2 ◽  
Normal Male ◽  
Converting Enzyme ◽  
Low Sodium ◽  
Converting Enzyme Inhibition ◽  
Male Subjects ◽  
Hypotensive Response

1. Because changes in the plasma concentration of angiotensin II and bradykinin appear inadequate to account completely for the hypotensive response to captopril, we measured changes in plasma prostaglandins in response to increasing doses of captopril in nine supine normal male subjects studied on both a high (200 mol/l) and low (10 mol/l) sodium intake. 2. On both the high and low sodium diets, captopril induced significant (P<0.01) increments in the 13,14-dihydro-15-keto metabolite of the vasodilatory prostaglandin E2, which correlated significantly with the fall in blood pressure (P<0.0001). 3. No significant changes were noted in the plasma levels of 6-keto-prostaglandins F1α or thromboxane B2, the stable products of prostacyclin and thromboxane A2 respectively.

Hypoxemia raises muscle sympathetic activity but not norepinephrine in resting humans

1989 ◽  
Vol 66 (4) ◽  
pp. 1736-1743 ◽  
Author(s):  
L. B. Rowell ◽  
D. G. Johnson ◽  
P. B. Chase ◽  
K. A. Comess ◽  
D. R. Seals
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Nervous Activity ◽  
Plasma Concentrations ◽  
Random Order ◽  
Sympathetic Nervous Activity ◽  
Severe Hypoxemia ◽  
Arterial Blood ◽  
End Tidal ◽  
Venous Plasma

The experimental objective was to determine whether moderate to severe hypoxemia increases skeletal muscle sympathetic nervous activity (MSNA) in resting humans without increasing venous plasma concentrations of norepinephrine (NE) and epinephrine (E). In nine healthy subjects (20–34 yr), we measured MSNA (peroneal nerve), venous plasma levels of NE and E, arterial blood pressure, heart rate, and end-tidal O2 and CO2 before (control) and during breathing of 1) 12% O2 for 20 min, 2) 10% O2 for 20 min, and 3) 8% O2 for 10 min--in random order. MSNA increased above control in five, six, and all nine subjects during 12, 10, and 8% O2, respectively (P less than 0.01), but only after delays of 12 (12% O2) and 4 min (8 and 10% O2). MSNA (total activity) rose 83 +/- 20, 260 +/- 146, and 298 +/- 109% (SE) above control by the final minute of breathing 12, 10, and 8% O2, respectively. NE did not rise above control at any level of hypoxemia; E rose slightly (P less than 0.05) at one time only with both 10 and 8% O2. Individual changes in MSNA during hypoxemia were unrelated to elevations in heart rate or decrements in blood pressure and end-tidal CO2--neither of which always fell. We conclude that in contrast to some other sympathoexcitatory stimuli such as exercise or cold stress, moderate to severe hypoxemia increases leg MSNA without raising plasma NE in resting humans.

Cardiovascular reflex responses in Bangladeshi and European subjects

1991 ◽  
Vol 80 (1) ◽  
pp. 39-45 ◽  
Author(s):  
M. A. Rahman ◽  
I. Farquhar ◽  
T. Bennett
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Vascular Resistance ◽  
Cardiovascular Responses ◽  
Mean Blood Pressure ◽  
Valsalva Manoeuvre ◽  
Deep Breathing ◽  
Reflex Responses ◽  
Forearm Vascular Resistance

1. Cardiovascular responses to three different interventions, namely the Valsalva manoeuvre, deep breathing and a cold stimulus on the face, were studied in two ethnic groups (European and Bangladeshi) that have been shown to differ in the prevalence of hypertensive-vascular disease. The data obtained consisted of systolic blood pressure, diastolic blood pressure, mean blood pressure, heart rate measured by using a beat-by-beat non-invasive blood pressure monitor (the Finapres), forearm blood flow determined by venous occlusion plethysmography, and calculated forearm vascular resistance. 2. The resting haemodynamic status was similar in European and Bangladeshi subjects. However, Bangladeshi subjects showed a greater increase in heart rate, but only after 20 s into the Valsalva manoeuvre, and greater overshoots in mean blood pressure after the manoeuvre than the European subjects. Furthermore, after cold face stimulation the fall in forearm vascular resistance to baseline levels was delayed in Bangladeshi subjects relative to that in the European subjects. 3. There were no inter-group differences in the reflex bradycardia relative to mean blood pressure or in the cardiac baroreflex sensitivity estimated from systolic blood pressure and pulse interval after the Valsalva manoeuvre. In addition, values for the mean difference between maximum and minimum pulse intervals during deep breathing did not differ in Bangladeshi and European subjects. 4. These findings together suggest that, although cardiac vagal reflex responses appear similar in the two groups, sympatho-adrenal influences on the heart and vasculature may be greater in Bangladeshi subjects than in European subjects.

Effect of Single and Combined Infusions of Angiotensin II and Aldosterone on Colonic Potential Difference, Blood Pressure and Renal Function, in Patients with Adrenal Deficiency

1975 ◽  
Vol 48 (3) ◽  
pp. 219-226
Author(s):  
A. D. Efstratopoulos ◽  
W. S. Peart
Keyword(s):  
Blood Pressure ◽  
Renal Function ◽  
Plasma Concentrations ◽  
Young Male ◽  
Normal Subjects ◽  
Potential Difference ◽  
Normal Male ◽  
Adrenal Deficiency ◽  
Increased Sensitivity ◽  
Male Subjects

1. The effect of single and combined infusions of angiotensin and aldosterone on colonic potential difference, blood pressure and renal function was studied in two normal male subjects and four female patients with adrenal deficiency maintained only on cortisone. 2. Aldosterone had its usual effect on colonic potential difference and it was possible to show that angiotensin had a small but definite effect of its own in the absence of aldosterone. The two hormones produced a summation response when given together. 3. The effects on renal function in two normal young male subjects were similar to those known previously. The response of the patients was different and probably reflected a number of factors, such as age, sex and long-standing adrenal deficiency. 4. Although the numbers were small, both normal subjects and patients showed a significantly greater rise of blood pressure with combined infusions of angiotensin and aldosterone than with angiotensin alone. The plasma concentrations of angiotensin were similar with both types of infusion, and so increased sensitivity to angiotensin in the presence of aldosterone is postulated.

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