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ENHANCEMENT EFFECT OF TETRAMETHYLPYRAZINE ON SLOW INWARD CURRENT IN GUINEA PIG PAPILLARY MUSCLES

Bai Qin, Tang Shumu

Department of Physiology,Henan Medical University Zhenzhou 450052

Abstract

Tetramethylpyrazine (TMP) could potentiate the force of contraction and increase the action potential duration (APD) of isolated guinea pig papillary muscles in a dosedependent manner. Similar effects were also observable in BaCl2 or histamine-induced contraction and the accompanied slow action potential (SAP). In fact，contraction and SAP could also be induced by TMP itself at 3. 0 mmol/L concentration and antagonized by verapamil(1 }tmol/L) within 10 min. In the presence of propranolol or in experiments carried out in.catecholamine-depleted (reserpine 2. 5 mg/kg，i. p. 15 h prior to
the experiment) muscles，TMP was unable to induce SAP and contraction. These results suggested that the effects of TMP on enhancing Is; were mediated by the release of catecholamine in myocardium.

Key words: :tetramethylpyrazine;Papillary muscles; action potential;myocardial contraction; calcium influx

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Citing This Article：

Bai Qin, Tang Shumu. ENHANCEMENT EFFECT OF TETRAMETHYLPYRAZINE ON SLOW INWARD CURRENT IN GUINEA PIG PAPILLARY MUSCLES. Acta Physiol Sin 1994; 46 (5): (in Chinese with English abstract).