The effects of sufentanil in the feline pulmonary vascular bed

The purpose of this prospective vehicle controlled study was to test the hypothesis that sufentanil induces a depressor response in the pulmonary vascular bed of the cat and identify the receptors involved in the mediation or modulation of these effects. In separate experiments, the effects of diphenydramine (histamine receptor blocker), glibenclamide (ATP-sensitive K+ channel blocker), L-N5-(1-Iminoethyl) ornithine hydrochloride (L-NIO) (nitric oxide synthase inhibitor), nimesulide (selective cyclooxygenase (COX)-2 inhibitor), and naloxone (opiate receptor antagonist) were investigated on pulmonary arterial responses to sufentanil and other agonists in the feline pulmonary vascular bed. The lobar arterial perfusion pressures were continuously monitored, electronically averaged, and recorded. In the feline pulmonary vascular bed of the isolated left lower lobe, sufentanil induced a dose-dependent vasodepressor response that was not significantly altered after administration of glibenclamide, L-NIO, and nimesulide. However, the responses to sufentanil were significantly attenuated following administration of diphenhydramine and naloxone. The results of the present study suggest that sufentanil has potent vasodepressor activity in the pulmonary vascular bed of the cat and that this response may be mediated or modulated by both histaminergic and opioid receptor sensitive pathways.