Studies on the hypotensive mechanisms of NZ-105, a new dihydropyridine derivative, in rats and rabbits.

1. Intravenous administration of NZ-105 caused a slow-onset and long-lasting hypotension in anesthetized SHR. 2. Centrally administered NZ-105 (0.04 mg/kg) slightly decreased blood pressure. 3. The hypotension of NZ-105 (0.1 mg/kg, i.v.) was not affected by atropine, propranolol, diphenhydramine plus cimetidine, aminophylline or indomethacin. 4. In ganglion-blocked rats, NZ-105 (0.003-0.3 mg/kg, i.v.) inhibited the pressor response to several hypertensive agents to a similar degree. 5. In pithed SHR, NZ-105 (0.03 mg/kg, i.v.) showed the same degree of hypotensive action as in non-treated SHR. 6. NZ-105 did not inhibit reflex responses to tilting in conscious rabbits. 7. Thus NZ-105 exerts its hypotensive action through the mechanisms of peripheral origin.