Calcium transport across avian uterus. II. Effects of inhibitors and nitrogen.

PEARSON, TERRY W., AND ANDREW M. GOLDNER. Calcium transport across avian uterus. II. Effects of inhibitors and nitrogen. Am. J. Physiol. 227(2) : 465-468. 1974.-Net calcium transport in the secretory direction occurs across the in vitro quail uterus in the absence of electrochemical gradients. The metabolic inhibitor, 2,4-dinitrophenol, and anaerobiosis reduced the net calcium transfer. The presence of the sulfhydryl agents, N-ethylmaleimide or p-chloromercuriphenylsulfonic acid, decreased the electrical potential difference as well as the short-circuit current. The net transfer of calcium was also decreased by both of these agents; however the onset of action of V-ethylmaleimide was more rapid. Ruthenium red, an inhibitor of’ Ca++-ATPase, had no effect on the transport of calcium or the electrical parameters of the uterus. Although ouabain in the presence of sodium reduced the calcium flux by 50?& in the absence of sodium, ouabain had no effect. The presence of the carbonic anhydrase inhibitor, acetazolamide, reduced net calcium transport to the same extent as removal of bicarbonate ion from the buffer. These results suggest that net calcium transport is active, requires oxidative aerobic metabolism, and is dependent on bicarbonate ion for maximal transfer.