The effects of calcium and vitamin D on blood pressure in conscious sheep.
The metabolic and haemodynamic effects of elevating plasma calcium levels were examined in both normal and ACTH-hypertensive sheep. Six weeks of dietary Ca++ supplementation did not alter plasma calcium levels, blood pressure or heart rate. Five days of CaCl2 infusion (2 mmol/h) or intravenous vitamin D injections elevated plasma ionised and total Ca++ levels and heart rate but mean arterial pressure was unchanged. As in other species, elevation of plasma Ca++ levels over 4 hours by infusion of CaCl2 at 2, 5, and 10 mmol/h increased mean arterial pressure and decreased heart rate. The course of ACTH-induced hypertension was not altered in animals supplemented with CaCl2 in their drinking water for 6 weeks nor by intravenous injection of vitamin D for 5 days. This study does not support a major role for altered plasma ionised or total Ca++ levels in the genesis of ACTH-dependent hypertension in the sheep.
Tresham
J J
JJ
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Australia.
McGuire
P
P
Coghlan
J P
JP
Whitworth
J A
JA
Scoggins
B A
BA
D000324:Adrenocorticotropic Hormone / Q000633:toxicity; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000097:blood / Q000494:pharmacology*; D002122:Calcium Chloride / Q000008:administration & dosage; D002136:Calcium, Dietary / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced; D007262:Infusions, Intravenous; D012756:Sheep; D014807:Vitamin D / Q000494:pharmacology*
D002136:Calcium, Dietary; D014807:Vitamin D; D000324:Adrenocorticotropic Hormone; D002122:Calcium Chloride; D002118:Calcium