Altered vascular responsiveness in isolated perfused lungs from aging rats.
Systemic vascular hyporesponsiveness has been well documented in aged rats, but a similar decreased vasoreactivity of the pulmonary vasculature has not been reported. Isolated lungs from young (3-5 months) and middle-aged (12-14 months) rats were perfused with whole blood and challenged alternately with alveolar hypoxia, angiotensin II, and 5-hydroxytryptamine. Hypoxic pulmonary vasoconstriction was less in the aging rats during both 5-min and 10-min hypoxic exposures. Likewise, log-dose response curves for angiotensin II and 5-hydroxytryptamine were right-shifted in the aging rats, indicating decreased responsiveness to the vasoactive agents. Since the vascular responses to all three vasoconstrictors were lower in the older animals, a generalized pulmonary vascular hyporeactivity with advancing age is suggested.
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000375:Aging; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure; D004305:Dose-Response Relationship, Drug; D008297:Male; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction
D000804:Angiotensin II; D006916:5-Hydroxytryptophan