Inhaled Y-27632 selectively decreased mean pulmonary arterial pressure without reducing systemic pressure in rat models of pulmonary hypertension, with a greater effect than inhaled nitric oxide.
Do inhaled Rho kinase inhibitors selectively reduce mean pulmonary arterial pressure in rat models of pulmonary hypertension?
Inhaled Rho kinase inhibitors act as potent and selective pulmonary vasodilators in rat models of pulmonary hypertension, suggesting potential utility for acute vasodilator testing in patients.
We have found in chronically hypoxic rats that acute intravenous administration of the Rho kinase inhibitor Y-27632 nearly normalizes the pulmonary hypertension (PH) but has no pulmonary vascular selectivity. In this study, we tested if oral or inhaled Y-27632 would be an effective and selective pulmonary vasodilator in hypoxic PH. Although acute oral Y-27632 caused a marked and sustained decrease in mean pulmonary arterial pressure (MPAP), it also decreased mean systemic arterial pressure (MSAP). In contrast, 5 minutes of inhaled Y-27632 decreased MPAP without reducing MSAP. The hypotensive effect of inhaled Y-27632 on hypoxic PH was greater than that of inhaled nitric oxide, and the effect lasted for at least 5 hours. Inhaled fasudil, another Rho kinase inhibitor, caused selective MPAP reductions in monocrotaline-induced PH and in spontaneous PH in fawn-hooded rats, as well as in chronically hypoxic rats. These results suggested that inhaled Y-27632 was more effective than inhaled nitric oxide as a selective pulmonary vasodilator in hypoxic PH, and that Rho kinase-mediated vasoconstriction was also involved in the other models of PH. Inhaled Rho kinase inhibitors might be useful for acute vasodilator testing in patients with PH, and future work should evaluate their efficacy in the long-term treatment of PH.
Nagaoka et al. (Wed,) conducted a other in Pulmonary hypertension. Inhaled Rho kinase inhibitors (Y-27632 and fasudil) vs. Inhaled nitric oxide was evaluated on Mean pulmonary arterial pressure (MPAP) and mean systemic arterial pressure (MSAP). Inhaled Y-27632 selectively decreased mean pulmonary arterial pressure without reducing systemic pressure in rat models of pulmonary hypertension, with a greater effect than inhaled nitric oxide.