Maintenance of arterial pressure by vasopressin and angiotensin II after adrenalectomy.

Abstract

SUMMARY Participation of vasopressin arid the renin-anglotensin system in the maintenance, of systemic arterial pressure was evaluated in unanesthetized adrenalectomized rats. Adrenalectomized and sham-operated rats with implanted arterial and venous catheters were given 1% sodium chloride and 2.5% glucose as drinking fluid for 72 hours following adrenalectomy. Serum and urine samples were obtained for measurement of electrolyte and solute concentration. The pattern of serum electrolytes, serum osmolality, and renal excretion of electrolytes, solute, and water observed in the adrenalectomized rats was entirely consistent with previous observations in this model. Mean arterial pressure of unanesthetized unrestrained adrenalectomized rats was significantly lower than controls. In adrenalectomized rats, dPMeTyrAVP reduced mean arterial pressure 9 ± 1 mm Hg, p < 0.001; captopril then caused an additional reduction of 17 ± 2 mm Hg, p < 0.01. Neither antagonist altered arterial pressure in the control group. Our results indicate that vasopressin and the renin-angiotensin system play a compensatory pressor role in adrenal insufficiency, preventing a larger decrease of arterial pressure in this model of chronic hypotension. son's disease) and adrenalectomized animals have a tendency to arterial hypotension. Activation of the renin-angiotensin pressor. system is a well-documented compensatory mechanism in both clinical and experimental adrenal insufficiency.1 -2 Circulating levels of vasopressin are elevated in clinical adrenal insufficiency 3 and in experimental forms of glucocorticoid and/or mineralocorticoid deficiency.4 " 6 A compensatory role for the pressor effect of vasopressin has been described in experimentally induced hypovolemic states such as dehydration in the rat 7 and hemorrhage in the dog 8 ' 9 by means of the use of specific antagonists of this hormone. Recently, it has been established that the increased circulating levels of vasopressin in adrenal insufficiency in dogs are high enough to exert a pressor effect. 6 We evaluated the contributions of both vasopressin and the renin-angiotensin system to maintenance of systemic arterial pres- sure in rats with experimental adrenal insufficiency by use of specific antagonists. Evidence is presented that both peptide systems participate in controlling arterial pressure in this model. MethodsFemale Sprague Dawley rats with an approximate weight of 250 g were placed in individual metabolic cages for a 3-day period of habituation after whicl v they underwent either adrenalectomy or sham adrerialectomy through a lumbar incision. Surgery was carried out during anesthesia with ketamine (100 mg/kg ip). At this time a Tygon (Norton) catheter was inserted into the left carotid artery and advanced to the thoracic descending aorta. Two catheters were inserted in the left jugular vein and advanced to the superior vena cava, just proximal to the right atrium., All three catheters were exteriorized at the back of the heck, filled with heparin (100 U/ml), and capped with pl...

Centrally Regulated Blood Pressure Response to Vasoactive Peptides is Modulated by Corticosterone

“…Mineralocorticoids and glucocorticoids secreted by the adrenal are crucial for cardiovascular homeostasis. In rats, removal of the adrenals leads to hypotension, but the decrease in blood pressure is counteracted by compensatory pressor influences of vasoactive agents (1). Aldosterone replacement still requires the participation of increased vasopressin and angiotensin II activity for maintenance of arterial pressure (2).…”

Electrocardiographic changes in the acute hyperkalaemia produced by intragastric KCl load in rats

“…However, removing the adrenal glands also eliminates the synthesis of catecholamines and cortisol (Beato et al, 1974;Borrell et al, 1983), leading, once again, to a non-specific and profound systemic challenge. Furthermore, removal of aldosterone compromises sodium homeostasis directly, because aldosterone is known to promote sodium appetite and reabsorption (Geerling & Loewy, 2008;Soundararajan et al, 2012), leading to severe hyponatraemia and hypotension (Elijovich et al, 1983).…”

In Memoriam: Fernando Elijovich

“…In his initial first-authored publication in Hypertension in 1983, he showed a compensatory role of vasopressin and the renin-angiotensin system in adrenal insufficiency and chronic hypotension. 1 In later publications in Hypertension , he revised our understanding of the use of ambulatory blood pressure monitors for screening and diagnosing hypertension in the clinic. 2 His work helped characterize essential hypertension in minorities, specifically in Hispanic patients who are disproportionally affected by hypertension and its related end-organ damage, and unearthed health care disparities in hypertension management in this population.…”