Pulmonary vasodilator responses to adrenomedullin are reduced by NOS inhibitors in rats but not in cats

The role of nitric oxide (NO) in mediating vasodilator responses to adrenomedullin (ADM), a hypotensive peptide derived from human pheochromocytoma cells, and the calcitonin gene-related peptide (CGRP) was investigated. Application of a NO synthase inhibitor on the lungs of rats and cats showed that NO mediate pulmonary vasodilator responses by dilating the pulmonary vascular bed of the rat during NO release, while in the cat, vasodilator responses to ADM and CGRP were independent of NO release. These results suggest that the role of NO in mediating vasodilator responses is species dependent.