Journal of cardiovascular pharmacology
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J. Cardiovasc. Pharmacol. · Nov 1995
Effects of pulmonary hypertension on vasoconstrictor responses to endothelin-1 and sarafotoxin S6C and on inherent tone in rat pulmonary arteries.
Vasoconstrictor responses to endothelin-1 (ET-1) and the ETB receptor agonist sarafotoxin S6c (SXS6c) were investigated in the main pulmonary artery and pulmonary artery branch removed from rats previously exposed to 10% O2 [chronic hypoxic (CH) rats] or room air (control rats) for 2 weeks. The effects of nitric oxide synthase (NOS) inhibition with L-Nomega-nitroarginine methyl ester (L-NAME) (100 microM) on ET receptor-induced responses in these arteries were also investigated. In control rats, in rings of main pulmonary arteries and pulmonary artery branches. ⋯ Pulmonary hypertension can potentiate ETA receptor-mediated vasoconstriction and facilitate ETB receptor-mediated vasoconstriction. Endogenous NO may normally suppress ETA receptor-mediated responses in rat main pulmonary arteries. Rat pulmonary arteries exhibit endogenous tone, which is increased by exposure to chronic hypoxia.