EFFECTS OF DIETARY VITAMIN-D DEFICIENCY ON THE CARDIOVASCULAR-SYSTEM

Experiments were performed on normotensive rats exposed to vitamin D d eficient and control diets from the 22nd to the 180th day of age. In 6 0-120- and 180-day-old rats. The following parameters were evaluated: a) The vasomotor responses elicited by receptor agonists in the absenc e and in the presence of the respective antagonists [L-norepinephrine (NE) before and 5 min after prazosin; L-isoprenaline (I) before and 5 min after DL-propranolol; L-dopamine (DA) before and 5 min after L-sul piride or SCH 23390 or chlorpromazine; acetylcholine (Ach) before and 5 min after atropine; histamine (H) before and after chlorpheniramine; 5-hydroxytryptamine (5-HT) before and 5 min after methysergide or ket anserin]; by carotid-sinus baroreceptor stimulation (CO) before and 5 min after hexamethonium, and by electrical stimulation of the vagus pe ripheral head (V) before and after atropine; b) Reflex tachycardia eli cited by bilateral carotid occlusion (CO) (for 40 sec) and by sodium n itroprusside; c) Catecholamine (norepinephrine, epinephrine) and argin ine-vasopressin plasma levels; d) Cholesterol, triglyceride and electr olyte (Na+, K+, Cl-, Ca2+) serum levels. Our results showed that vitam in D deficient diets induced a decrease in presser responses to NE and CO, and an increase in hypotensive responses to I, DA, Ach, H, 5-HT a nd V. Changes of arterial blood pressure, heart rate, catecholamine an d arginine-vasopressin plasma levels were not observed. Cholesterol, t riglyceride and electrolyte (Na+, K+, Cl-) serum levels were not modif ied, while Ca2+ serum levels decreased. In conclusion, our data sugges t that vitamin D depletion can induce changes of presser and depressor vasomotor responses and suppose a direct role for vitamin D in regula ting vasomotor reactivity.