Effects of vasodilators on fibrin-induced pulmonary edema, so-called neurogenic pulmonary edema, in the rat

Abstract

The present study was undertaken to evaluate the effects of vasodilators on the development of neurogenic pulmonary edema. Pulmonary edema was induced by injecting fibrinogen and thrombin into the cisterna magna of vagotomized rats (fibrin-induced pulmonary edema). Before the intrathecal injections, rats were pretreated with intravenous injection of one of the following vasodilators: phentolamine, isoproterenol, nifedipine, diltiazem, isosorbide dinitrate, or substance P. Each vasodilator reduced the incidence of fibrin-induced pulmonary edema and lung-water ratio dose-dependently except nifedipine and diltiazem. There was a uniform relationship between the lung-water ratio and the prefibrin mean arterial pressure obtained under administration of different doses of the each drug. A similar relationship was obtained even if the drug used was different. Treatment with nifedipine or diltiazem, however, diminished the blood pressure but provided less protection against the development of pulmonary edema. The blood volume in edema-positive lungs was minimally different from that in edema-negative lungs. These results suggest that the neurogenic pulmonary edema may be effectively prevented by most vasodilators except Ca⁺⁺-blockers.