saralasin and argipressin--beta-mercapto-beta-beta-cyclopentamethylenepropionic-acid(1)-

Xeric-adaptation was studied during 28 days of total water deprivation (TWD) in Notomys alexis. Beyond 7 days, the initial reductions in body weight and increases in haematocrit, plasma renin and juxtaglomerular (JG) cell morphological activity returned to normal. Mus musculus showed similar changes at 7 days but could not be maintained thereafter. TWD decreased the blood pressure of Notomys but endogenous angiotensin and vasopressin did not support pressure to a greater extent than controls, as revealed by selective antagonists. The normal morphology of the JG apparatus in Notomys was similar to other rodents. Fluid volume and blood pressure maintenance during TWD in Notomys do not depend upon enhanced activities of the renin-angiotensin and antidiuretic hormonal systems.

Topics: Adaptation, Physiological; Animals; Arginine Vasopressin; Blood Pressure; Body Weight; Enalaprilat; Hematocrit; Juxtaglomerular Apparatus; Male; Mice; Mice, Inbred BALB C; Renin; Rodentia; Saralasin; Vasopressins; Water Deprivation

The contribution of the autonomic nervous system, angiotensin II (ANG II), and arginine vasopressin (AVP) to the control of blood pressure (BP) was examined in 12 chronically instrumented tethered monkeys. The vasopressin antagonist, [d(CH2)5AVP] (Manning Compound, MC), the ANG II antagonist, saralasin (SAR), and the ganglionic blocking drug, hexamethonium (Hx), were injected in a random sequence into the left atrium (LA) while BP and heart rate (HR) were monitored. When given as the first antagonist, MC caused a slight decrease in BP; SAR did not significantly decrease BP regardless of the sequence of administration, whereas Hx caused a consistent decrease in blood pressure of 35-50 mmHg. Seven (4 intact and 3 with renal denervation) additional animals were involved in hemorrhage experiments. Blood pressure was reduced to 50-60 mmHg by hemorrhage and then allowed to return spontaneously. Ten to 15 min after the end of the hemorrhage, MC was given. When blood pressure had stabilized, SAR was given. Blood pressure returned to 80-90 mmHg after the hemorrhage. MC did not affect the blood pressure recovery; however, saralasin reduced it to the post-hemorrhage levels. We would conclude that the sympathetic nervous system is the primary controlling mechanism for BP in the conscious primate, with AVP making a minor contribution. The release of renin would appear to be primarily under the control of the sympathetic nervous system.

Topics: Animals; Antihypertensive Agents; Arginine Vasopressin; Autonomic Nervous System; Blood Pressure; Denervation; Female; Hemorrhage; Hexamethonium; Hexamethonium Compounds; Kidney; Macaca mulatta; Male; Renin-Angiotensin System; Saralasin