Dipyridamole suppresses catecholamine- and Ca++ influx-sensitive ventricular arrhythmias.
To study the mechanism of ventricular arrhythmias, the effect of dipyridamole (DIP; 300 mg/day), an adenosine transport inhibitor, on ventricular premature contractions (VPCs) was assessed in 12 patients who showed VPCs (21312 +/- 12314/day) on Holter ECG in a controlled setting. The effects were compared with those of verapamil (240 mg/day) and bisoprolol (5 mg/day). DIP suppressed more than one-half the VPCs in 5 patients. The mean degree of reduction in these DIP-responders was 75 +/- 18%. Both verapamil and bisoprolol inhibited VPCs in all of the DIP-responders (verapamil: 71 +/- 15%, bisoprolol: 88 +/- 16%). Two of the 5 DIP-responders had sustained ventricular tachycardias (VT) that were terminated by intravenous DIP, ATP, acetylcholine, verapamil, and propranolol. In contrast, verapamil did not inhibit VPCs in any of the DIP-nonresponders. Bisoprolol also did not suppress VPCs in 3 of 6 DIP-non responders. heart rate was unaffected by DIP, but was suppressed by both verapamil and bisoprolol. In addition, DIP increased the serum concentration of adenosine (control 16.3 +/- 17.1 vs 22.3 +/- 19.0 pmol/ml after DIP, p < 0.05). The inhibitory effect of DIP may involve suppression of Ca+2 current through an extracellular increase in adenosine.
Third Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan.
Y
Y
Kobayashi
A
A
Miyata
K
K
Chiyoda
H
H
Nakagawa
Y
Y
Jinbo
K
K
Tanno
S
S
Kikushima
K
K
Kurano
T
T
Baba
T
T
Katagiri
D000328:Adult; D000368:Aged; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D004176:Dipyridamole / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*; D014693:Ventricular Fibrillation / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D014700:Verapamil / Q000494:pharmacology / Q000627:therapeutic use
D002395:Catecholamines; D014665:Vasodilator Agents; D004176:Dipyridamole; D014700:Verapamil; D002118:Calcium