The role of some activators and inhibitors of calcium channels on the dynamics of serum magnesium.

: Magnesemia was determined in male rats weighting 120 +/- 10 g after intravenous administration of nifedipine, an antagonist of calcium channels, and BAY-K 8644, an activator of calcium channels. Nifedipine does not alter the basal level of serum Mg 30 minutes after administration in normal animals or in animals in which chemical sympathectomy was induced by administration of 6 OH-dopamine. On the other hand, BAY-K 8644 induces a significant rise of basal magnesemia from 2.1 +/- 0.2 mg% to 2.7 +/- 0.1 mg% in normal animals. In animals sympathectomized with 6 OH-dopamine, their rise is maintained at about the same level from 2.0 +/- 0.1 mg% after administration). Propranolol previously administered inhibits the stimulating action induced by the calcium channel agonist, BAY-K 8644.