| Abstract: | Various fractions of alcoholic extract of Pimelea trichostachya were prepared and three of these were compared in terms of (a) ability to produce sustained contraction of spiral muscle of bovine pulmonary vein in vitro, (b) LD50 values in mice by intraperitoneal injection and (c) acute toxicity by intravenous injection into calves. Good agreement was observed between activity of the fractions in all three systems, thus providing further evidence for the role of pulmonary venous hypertension in the pathogenesis of at least part of the syndrome of Pimelea poisoning in the bovine. The most toxic of the fractions was shown by chronic intoxication of a calf to be capable of producing most of the features of the natural disease. |
