INFLUENCES OF DIFFERENT ANTIHYPERTENSIVE TREATMENTS ON INDEXES OF SYSTEMIC MINERAL METABOLISM

A negative calcium balance has previously been described in human hype rtension with low levels of plasma ionized calcium (Ca2+) and an incre ased urinary excretion of calcium. The cause of this disturbance in mi neral metabolism is not known, nor is it known if this derangement cou ld be abolished if blood pressure is reduced by antihypertensive treat ment. In the present investigation, the effects of antihypertensive mo notherapy on serum and fasting urinary electrolytes were studied. For 3 to 6 months, 319 hypertensive patients entered 17 study groups, each group using one of the following antihypertensive drugs: dilevalol, m etoprolol, atenolol, pindolol, propranolol, hydrochlorothiazide, bendr ofluomethiazide, furosemide, spironolactone, doxazocine, prazocine, di ltiazem, verapamil, nifedipine, isradipine, captopril, or lisinopril. Treatment with different beta-blockers, as well as diuretics, reduced the fasting urinary calcium excretion (P < .001). However, while the b eta-blockers increased the proportion of the ionized form of calcium i n blood (Ca2+) (P < .001), Ca2+ was further decreased by diuretic trea tment (P < .05). Angiotensin converting enzyme inhibitors caused no ma jor changes in mineral metabolism while of the calcium antagonists stu died only verapamil raised the levels of Ca2+ (P < .01). No significan t relationship between the changes in mineral metabolism and the reduc tion in blood pressure was observed in any of the treatment groups. Of the antihypertensive drugs used in the present study, beta-blockers a ppeared to reverse the basic abnormality with regard to calcium balanc e, suggesting that the activity of the sympathetic nerve system is inv olved in the disturbed calcium metabolism seen in hypertensive patient s.