Effects of calcium and its antagonists on hemodynamics and respiration

Acute tests on cats under Nembutal anesthesia show that intravenous injection of Ca²⁺ causes pathological respiration of the apneustic type and slight rises in pulmonary and arterial pressures. The calcium channel blockers verapamil and nifedipine decrease the amplitude of respiratory movements, increase the respiration rate and pulmonary pulse pressure, and lower systemic pressure. The introduction of verapamil or nifedipine into the fourth ventricle of the brain does not alter respiration or hemodynamics, whereas the introduction of Ca²⁺ leads to irreversible respiratory standstill. Hemodynamic parameters decrease 2–3 min after the respiratory standstill. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 8, pp. 138–143, August, 1996