1. The peripheral blood concentrations of aldosterone, corticosterone and cortisol were measured during pregnancy in conscious, undisturbed sheep. 2. Aldosterone levels did not change during pregnancy and the mean pregnant value, 1-2 s.d. 1-4 ng/100 ml(n = 12) was not significantly different from the non-pregnant value, 2-1 s.d. 1-7 (n = 16). 3. Cortisol levels likewise were unchanged by pregnancy-non-pregnant values were 0-56 s.d. 0-50 mug/100 ml (n = 12) compared with 0-46 s.d. 0-40 mug/100 ml (n = 16) in pregnant sheep. 4. Sheep of 110-140 days gestation had a 400 mmol greater total exchangeable sodium than non-pregnant sheep. Plasma volume and plasma renin concentration tended to be elevated near to term. 5. Very high aldosterone secretion rates and peripheral blood levels could be produced in pregnant sheep by stress, intravenous ACTH or angiotensin II infusions, and by sodium deficiency. It is suggested that the pregnant sheep may show increased sensitivity in contrast to non-pregnant sheep to these stimuli and the enlarged size of their adrenals may be a contributing factor.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

Renal autotransplants in sheep: investigation of renal function and renovascular hypertension.

1. A novel surgical preparation of sheep with a cervical renal autotransplant has been developed. 2. Glomerular filtration rate and effective renal plasma flow were 25.1 +/- 1.0 ml/min and 208 +/- 10 ml/min respectively (n = 26). 3. The responses to water load and deprivation, to AVP injection, to Na depletion and intravenous hypertonic saline load show the kidneys responded in an appropriate physiological manner. 4. Constriction of the carotid-renal artery to reduce mean renal arterial pressure to 23 +/- 4 mmHg (n = 4) resulted in an increase in systemic mean arterial pressure from 70 +/- 4 mmHg to 75 +/- 4 mmHg within 5 min. Systemic blood pressure further increased to 110 +/- 7 mmHg with 2 h of constriction, when renal arterial pressure had increased to 45 +/- 2 mmHg.

Animals↗

PubMedDate not supplied

A comparison of two macroscopic platelet agglutination assays for von Willebrand factor.

Plasma drawn from 22 patients with a broad range of von Willebrand factor (vWF) levels, including one patient with rare, severe type III von Willebrand's disease, was used to investigate the adaptability of the Bio/Data Corp. vW Factor Assay, a ristocetin cofactor-based kit developed for use with a platelet aggregometer, to a macroscopic platelet agglutination technique. The results were compared to those obtained using the General Diagnostics von Willebrand Factor Assay, another ristocetin cofactor-based kit developed for use as a macroscopic platelet agglutination procedure. No significant difference (p greater than 0.5) existed between results obtained by these two kits. The mean and standard deviation of the vWF levels (as percent of normal) were 132 +/- 66.7 by the General Diagnostics kit and 133 +/- 59.0 by the Bio/Data Corp. kit. The correlation coefficient (r) was 0.81. The Bio/Data Corp. kit is more costly per test than the General Diagnostics kit. However, it was shown to be compatible with the macroscopic agglutination technique and required no modification to be used in that manner.

Female↗

PubMedDate not supplied

Alterations in osmotic but not pressor responses to ACTH by optic recess lesions in sheep.

This study examines whether neural structures in the region of the optic recess of the third ventricle may be involved in the genesis of adrenocorticotrophic hormone (ACTH)-induced hypertension in sheep. Five sheep were prepared with lesions in an area of the forebrain that included the organum vasculosum of the lamina terminalis (OVLT) and surrounding periventricular tissue. In these animals the dipsogenic response to systemically infused hypertonic sodium chloride (NaCl) was abolished. ACTH treatment (20 micrograms/kg/day) for 5 days caused an increase in mean arterial pressure (MAP) of 19 mm Hg, a response identical to that seen in normal sheep. With ACTH treatment, increases in plasma osmolality were greater than normal, but polydipsia did not occur in the lesioned sheep. In six other sheep with lesions either lateral or anterior to the optic recess of the third ventricle, the dipsogenic response to hypertonic NaCl and pressor response to ACTH were normal. These studies establish that in ACTH-treated sheep the integrity of the anterior ventral part of the third ventricle is not essential for the development of the hypertension. This is in contrast to the finding in other models of experimental hypertension in the rat.

Adrenocorticotropic Hormone↗