Coronary spasm produced by picrotoxin in cats.

Picrotoxin (2 mg/kg i.v.) was administered to 6 vagotomized chloralose-anesthetized cats while monitoring coronary blood flow (electromagnetic flow probe), blood pressure and ECG. Coronary constriction occurred in each animal as measured by an increase in coronary vascular resistance (CVR) (mean = 25.2 +/- 7.5%, P less than 0.05) followed by ST segment elevation (0.30 +/- 0.06 mV, P less than 0.05). Pretreatment with phentolamine prevented the increase in CVR and the elevation in ST segment. These results demonstrate that picrotoxin produces alpha-receptor mediated coronary spasm.