The effect of pressure loading on the blood flow rate in human skin.

The effect of pressure on the blood flow in skin is of considerable clinical interest. Methods are described for the estimation of skin blood flow from the disappearance rate of an injection of 133Xe in saline. The flow rate may be monitored for a period long enough to establish the normal flow and the reduced flow resulting from a constant pressure load.

Blood pressure response to acute changes in dietary sodium in young Zimbabwean men.

Objective: The primary objective of this study was to determine the effect of acute alterations in sodium intake upon the blood pressure and hormone levels of young Zimbabwean men.

Design: Blood pressure, 24-h urinary electrolyte excretion and plasma concentrations of angiotensin II, aldosterone, and atrial natriuretic peptide were measured in normotensive black medical students. Three sets of measurements were taken: (1) during free access to sodium (baseline); (2) after 4 days on a low-sodium diet (10 mmol/day); and (3) after 4 days on a high-sodium diet (800 mmol/day).

Hemodynamic and behavioral effects of angiotensin II in conscious sheep.

Intracerebroventricular (ivt) angiotensin II (ANG II) at 0.4, 2, 10, and 50 ng.kg-1.

Plasma atrial natriuretic peptide in conscious rats with reduced renal mass.

The effect of salt intake and reduction of renal mass (RRM) on plasma immunoreactive atrial natriuretic peptide (iANP) levels in conscious rats was studied. Rats were divided into RRM and sham-operated groups, and then further subdivided into groups infused with 1 or 6 mEq of sodium per day. Plasma urea nitrogen increased in the groups with RRM.

Comparison of intracerebroventricular and intracarotid infusions of PGE2 in conscious sheep.

Conscious sheep chronically prepared with nonocclusive indwelling vascular and cerebroventricular catheters were used to compare hemodynamic, hematologic, hormonal, and behavioral responses of intracarotid (ic) prostaglandin E2 (PGE2) to intracerebroventricular (ivt) PGE2. PGE2 had less potent hemodynamic effects when infused ivt than when infused ic. Intracarotid PGE2, 100 ng.

Alpha-human atrial natriuretic peptide is a coronary vasodilator in the Langendorff-perfused guinea pig heart.

The circulating form of atrial natriuretic peptide is now believed to be composed of 28 amino acids (1). Therefore, we studied the coronary vasoactivity of the 28 amino acid, alpha-human atrial natriuretic peptide (alpha-hANP) in five isolated guinea pig hearts Langendorff-perfused at constant pressure (46 mmHg) with Krebs-Henseleit solution. The reactivity of the coronary bed was assured in each heart with bolus injections of norepinephrine, adenosine, and the vasoconstrictor atrial natriuretic peptide, atriopeptin II (APII).

Central angiotensin II and PGE2 act independently to increase blood pressure in conscious sheep.

Conscious adult female sheep chronically prepared with nonocclusive indwelling vascular and cerebroventricular catheters were used to determine whether centrally administered prostaglandin E2 (PGE2) increases blood pressure by activation of the brain renin angiotensin system or whether centrally administered angiotensin II (ANG II) increases blood pressure by stimulating prostaglandin synthesis in the brain. Intracerebroventricular (ivt) ANG II, 50 ng X kg-1 X min-1, increased arterial pressure 23 mmHg (P less than 0.01) 30 min after the start of infusion.

Atriopeptin II lowers cardiac output in conscious sheep.

Atrial natriuretic peptides cause natriuresis, kaliuresis, diuresis, and hypotension. They relax vascular smooth muscle in vitro, and they dilate renal vessels in vivo. Hence, we tested the hypothesis that they produce hypotension by lowering total peripheral resistance.

Coronary vasoconstrictor effects of atriopeptin II.

Atrial natriuretic peptides lower arterial pressure, cardiac filling pressure, and cardiac output. In isolated, Langendorff-perfused guinea pig hearts, atriopeptin II, the 23-amino acid atrial natriuretic peptide, is also a potent coronary vasoconstrictor. The median effective dose for atriopeptin II in guinea pig hearts is 26 nanomoles, the threshold constrictor dose is 5 nanomoles, and flow nearly ceases at a dose of 100 nanomoles in perfused hearts at constant pressure.

Mechanism of tachycardia caused by intracarotid PGE2 in conscious ewes.

Conscious adult ewes prepared with nonocclusive indwelling vascular catheters were used to determine the mechanism by which heart rate increases during central administration of prostaglandin E2 (PGE2). Heart rate increased 14 bpm during steady-state intracarotid infusion of PGE2, 10 ng/kg/min (P less than 0.05).

Mechanisms of central prostaglandin E2 hypertension in conscious dogs, sheep, and calves.

Intracarotid prostaglandin E2 (PGE2) infusions (10 ng X kg-1 X min-1) increased arterial pressure in conscious dogs, sheep, and calves. Total and regional peripheral resistances (renal, superior mesenteric, and iliac) increased in conscious calves. Arterial pH and CO2 tension did not change, implying no activation of the chemoreflex.

Cardiac atria of BIO 14.6 hamsters are deficient in natriuretic factor.

The hearts of 220-day-old hamsters of the BIO 14.6 strain are deficient in atrial natriuretic factor; saline extracts of atria produce one-third the natriuretic and diuretic effects of extracts of atria from age-matched normal hamsters. BIO 14.

PGE2 does not act at carotid sinus to raise arterial pressure in conscious sheep.

Conscious chronically instrumented adult female sheep were used to determine whether direct action of prostaglandin E2 (PGE2) on the carotid sinus baroreceptors contributes to the pressor response observed during infusion of PGE2 into the common carotid artery (CCA). During infusion of PGE2 into the CCA caudal to an intact carotid sinus, into the CCA caudal to a denervated carotid sinus, and into the external carotid artery, mean arterial pressure (MAP) rose 17, 22, and 17 mmHg, respectively (P less than 0.01).

Hemodynamics of high afterload left heart failure for assist device testing.

The hemodynamic responses to increased afterload of the left ventricle were studied in conscious calves during exercise. The calves were chronically instrumented to measure (or derive) heart rate, stroke volume, cardiac output, iliac, superior mesenteric and renal flows and resistances, mean carotid, aortic, right atrial, pulmonary artery, and left atrial pressures, the systemic and pulmonary pressure gradients, and total systemic and total pulmonary resistances. The calves were also instrumented to produce reversible partial constriction of the ascending aorta and common carotid arteries and for cooling of the cervical vagus nerves.

Cardiac and sinoaortic reflexes during aortic constriction in awake calves.

The hemodynamic responses to increased afterload of the left ventricle were studied in conscious calves before and during cooling of the cervical vagus nerves bilaterally. The calves were chronically instrumented to measure (or derive) heart rate, stroke volume, cardiac output, iliac, superior mesenteric and renal flows and resistances, mean aortic, right atrial, pulmonary artery, and left atrial pressures, the systemic and pulmonary pressure gradients, and total systemic and total pulmonary resistances. The calves were also instrumented to produce reversible partial constriction of the ascending aorta and for cooling of the cervical vagus nerves.

In vitro evaluation of U.S. and U.S.S.R. artificial hearts.

This report summarizes the results of the in vitro evaluation of Soviet and American artificial hearts. The devices were tested at the All-Union Institute of Transplantation and Artificial Organs, Moscow, U.S.

Comparison of tissue-cultured bovine endothelial cells from aorta and saphenous vein.

Endothelial cells were harvested from bovine aorta and saphenous vein with collagenase and cultured in McCoy's 5a medium (modified GIBCO) supplemented with 10% fetal bovine serum. The cells were subcultured through 17 passages over 4 to 5 months. The growth properties in culture of the two cell types were compared.

Endothelial cell culture on dacron fabrics of different configurations.

The growth of tissue-cultured aortic endothelial cells from the calf using 12 different configurations of Dacron polyester (U.S. Catheter and Instrument Co.

Forty-one variables following thoracotomy in calves.

Seven calves underwent thoracotomy to study the response of 41 physiologic variables over a 14 day post-operative period for comparison to a recent series of left ventricular bypass pump implants. The experimental protocols were identical to the pump implant protocols except that the sham operated animals did not receive antiplatelet or anticoagulant drugs and the pumps were not implanted. Of the 41 variables studied, 13 changed significantly during the post-operative period.

Left ventricular failure in calves produced by supravalvular aortic stenosis.

A stable model of left ventricular failure is required to test left ventricular assist devices. Supravalvular aortic constriction will cause left atrial pressure to rise to new levels which are stable for several days. When left atrial pressure becomes unstable, an automatically actuated left ventricular assist device will increase its output and prevent pulmonary edema.

Recent experience with the Baylor left ventricular bypass pump.

The current Baylor left ventricular bypass pump is a pneumatically actuated diaphragm pump lined with segmented polyurethane. It is a swirl design in which blood moves in a circular motion within the pump. It has tilting disc inflow and outflow valves and the stroke volume is 60 ml.

Effects of external pressure loading on human skin blood flow measured by 133Xe clearance.

Forearm skin blood flow was measured during external pressure loading in normal human subjects using 133Xe washout from intracutaneous injection sites. Pressures ranging between 5 and 150 mmHg were applied through a 3-cm-diameter disc placed over the site of flow determination. The pressure was maintained constant by a servo-controlled loading mechanism.

Effect of ketamine on ventricular dynamics of unanesthetized baboons.

Ketamine hydrochloride is commonly employed to sedate or anesthetize laboratory primates but its cardiac actions have not been previously described in these animals. Four baboons, Papio cynocephalus, were chronically instrumented with electromagnetic flow detectors on the ascending aorta and common carotid artery. Cardiac output, peak aortic flow velocity and peak aortic flow acceleration are all depressed by Ketamine, 5 mg/kg i.

Effect of fluocinolone acetonide cream on human skin blood flow.

Blood flow rate was measured in the forearm skin of human subjects exposed to ultraviolet irradiation. Blood flow was determined by the 133Xe disappearance technique 18 hr after ultraviolet (UV) irradiation with a Westinghouse RS sunlamp held 10 inches from the skin for 10 min. Ultraviolet irradiation caused skin blood flow to increase.

Correlation of peak aortic and carotid flow acceleration during coronary occlusion in conscious baboons.

1. Peak blood flow acceleration measured in the common carotid artery was compared with peak flow acceleration measured in the ascending aorta of three baboons. 2.