Pulmonary vasodilation in the rat by insulin in vitro could indicate potential hazard for inhaled insulin.
OBJECTIVE
Hypoxic pulmonary vasoconstriction is an essential mechanism to prevent hypoxaemia in lung diseases. Insulin is known to be a systemic vasodilator but its effect on the pulmonary circulation is not known. Inhaled particulate insulin can generate locally high concentrations in the lung which could be physiologically important.


METHODS
We therefore studied the effects of insulin in vitro on isolated rat pulmonary artery in a small vessel myograph.


RESULTS
We have shown that pulmonary artery vasodilatation with insulin occurs in a dose-dependent manner. Pre-constriction with PGF2alpha can be abolished (105.7+/-2.9%, mean+/-SEM) and pre-constriction with hypoxia reduced (68.9+/-6.5%) by pharmacologically relevant concentrations of insulin. The characteristic phasic vasoconstriction by pulmonary vessel to hypoxia is substantially modified, resulting in sustained vasodilatation.


CONCLUSIONS
These effects could be clinically important for patients using inhaled insulins who have acute or occult chronic lung disease.
Aye
M
M
Academic Department of Medicine, University of Hull, Hull, UK.
Sheedy
W
W
Harrison
R
R
Thompson
J S
JS
Morice
A H
AH
Masson
E A
EA
D000818:Animals; D015237:Dinoprost / Q000494:pharmacology; D000860:Hypoxia; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
D007328:Insulin; D015237:Dinoprost