Calcium entry blocking activity of adenosine potentiating compounds in guinea pig taenia coli

Calcium entry blocking activities of adenosine and its potentiating drugs, dilazep, lidoflazine and dipyridamole, were studied in potassium (100 mM)-depolarized guinea pig taenia coli, and compared with nifedipine, verapamil and diltiazem. The potency ratio of calcium entry blocking effect of nifedipine, diltiazem, lidoflazine and dilazep to verapamil was 158.5, 1/1.1, 1/15.8 and 1/81.3, respectively. Dipyridamole and adenosine had negligible calcium entry blocking effects.