NEGATIVE INOTROPIC EFFECT OF ZINC SULFATE IN ISOLATED GUINEA PIGS ATRIA
Ma Xin, Li Xiaoguang (Research Laboratory of Electrophysiology, Xian Medical University, Xian 710061)
Zinc sulfate 0.1mmol/L inhibited the frequency dependent positive staircase phenomenon on isolated guinea pig atria. Ten min after adding zinc sulfate 0.1 mmol/L, the contractility of the left atrium decreased. The needed concentration of epinephrine inducing automaticity was increased and the functional refractory period(FRP) was prolonged from 192?5 ms to 247±4 ms ( P0.01). Ten min after zinc sulfate 0.3 mmol/L was administrated the post-rest potentiation was markedly inhibited, calcium dose-response curves were shifted noncompetitively to the right, and the maximal response was depressed. The results indicate that zinc sulfate may influence Ca2+ movement in cells.