Hormonal changes associated with hypertension in neoplasia-induced hypercalcemia.

Neoplasia-induced hypercalcemia in the Fischer rat results in hypertension 1 wk after Leydig cell tumor transplantation. Systolic blood pressure, plasma catecholamine, prolactin, plasma renin activity (PRA), and aldosterone responses to immobilization stress were evaluated in Fischer rats 10 days after tumor transplantation and in age-matched nontransplanted controls. Basal systolic blood pressure, norepinephrine, and PRA levels at 10 days after tumor transplantation were higher in association with elevated calcium levels in tumor-transplanted rats than in controls. Systolic pressure, norepinephrine, and epinephrine responses to immobilization stress were greater in the hypercalcemia 10-day transplanted rats. Although basal levels of prolactin and aldosterone were similar in the two groups. These observations suggest that elevated levels of the vasoactive hormones norepinephrine and angiotensin may play a pivotal role in development of hypertension in association with neoplasia-induced hypercalcemia. Further, neoplasia-induced hypercalcemia in the Fischer rat is associated with a relative hyperreninemic hypoaldosteronism state.