Abstract
Effects of nitroglycerin on the 45Ca efflux were studied on the isolated coronary artery preparation of the dog. After loading with 45Ca for 3 hours and rinsing with cold physiological salt solution (PSS), the preparation was transferred to a series of vials containing oxygenated PSS at 10 min intervals. After 100 min, Ca efflux was induced from within the cell by metabolic inhibition with dinitrophenol plus monoiodoacetate following the method of Van Breemen et al. (1975). Nitroglycerin did not produce any effect on the Ca efflux. Although not complete, lanthanum (1 mM) produced an inhibition of the Ca efflux, which was not reversed by nitroglycerin. It is concluded that our previous findings of relaxation of the lanthanum contracture of the coronary artery by nitroglycerin was not brought about by an increase in Ca efflux from the coronary artery.
