Isovolumetric indices and humoral cardioactive substance bioassay during clinical and experimentally induced gastric dilatation-volvulus in dogs.

Plasma collected from 6 experimentally induced and 29 clinical cases of gastric dilatation-volvulus was assayed for cardioactive substances utilizing isolated canine papillary muscles. The results were correlated with in vivo isovolumetric indices of myocardial contractility observed during experimental gastric dilatation-volvulus in the dog. Cardioactive substances were not detected during experimental gastric dilatation-volvulus. Two experimental dogs showed a cardiostimulatory response and 4 experimental dogs showed a cardiodepressant response following gastric decompression. Cardioactive substance bioassays correlated well with isovolumetric indices in experimental dogs. The variable response in cardioactive substance bioassay observed in experimental dogs was consistent with clinical gastric dilatation-volvulus bioassays which produced a widely variable response ranging from strongly cardiostimulatory to strongly cardiodepressant.