Effects of Antiproteases (Aprotinin and Gabexate-Mesilate) on the Postischemic Vascular Response of the Kidney

Abstract

Both under physiologic conditions and after short-term ischemia (1–3 min) kallikrein and locally synthesized prostaglandins contribute to control renal blood flow. In the present experiment the antiproteases aprotinin and gabexate-mesilate were administered to rabbits in an attempt to show whether the hemodynamic changes produced by 60 min of normothermic ischemia, i.e., postischemic hyperemia and reduction of vascular resistance, were equally mediated by kallikrein. Vascular responses were evaluated by determining renal cortical blood flow using radioactively labelled microspheres, by calculating vascular resistances, and by measuring the diameters of renal medullary vessels. Kidneys exposed to normothermic ischemia and sham-operated control organs of animals treated with aprotinin (2 × 40,000 KlU/kg body weight) and gabexate-mesilate (2X7 mg/kg body weight) were compared with those of rabbits which were analogously operated, but did not receive any drugs. As the antiproteases used did not significantly affect the hyperemia and the reduction of renal cortical vascular resistance seen after 60 min of normothermic ischemia, these phenomena are apparently not mediated by kallikrein. Renal medullary vasodilatation (arteriolae rectae) was significantly lower under aprotinin than in untreated ischemic kidneys, and was not longer demonstrable in gabexate-mesilate-treated animals. Thus, the effect of gabexate-mesilate was superior to that of aprotinin. Whether the antiprotease action is due to an unspecific membrane-stabilizing, to a general ezyme-inhibiting, or to a specific kallikrein-inhibiting effect, is still unclear.