Zusammenfassung
PURPOSE. To identify the alpha(1)-adrenoceptor (alpha(1)-AR) subtypes mediating vascular adrenergic responses in murine ophthalmic arteries. METHODS. Expression of mRNA was quantified for individual alpha(1)-AR subtypes in murine ophthalmic arteries using real-time PCR. To assess the functional relevance of alpha(1)-ARs for mediating vascular responses, ophthalmic arteries from mice deficient in ...
Zusammenfassung
PURPOSE. To identify the alpha(1)-adrenoceptor (alpha(1)-AR) subtypes mediating vascular adrenergic responses in murine ophthalmic arteries. METHODS. Expression of mRNA was quantified for individual alpha(1)-AR subtypes in murine ophthalmic arteries using real-time PCR. To assess the functional relevance of alpha(1)-ARs for mediating vascular responses, ophthalmic arteries from mice deficient in one of the three alpha(1)-AR subtypes (alpha(1A)-AR(-/-), alpha(1B)-AR(-/-), and alpha(1D)-AR(-/-), respectively) and wild-type controls were isolated, cannulated with micropipettes, and pressurized. Changes in luminal artery diameter in response to the alpha(1)-AR agonist phenylephrine, the sympathetic transmitter noradrenaline, and to the nonadrenergic vasoconstrictor arginine vasopressin (AVP) were measured by video microscopy. RESULTS. Using real-time PCR, mRNA for all three alpha(1)-AR subtypes was detected in ophthalmic arteries from wild-type mice. In functional studies, phenylephrine and noradrenaline produced dose-dependent constriction of ophthalmic arteries that was similar in wild-type, alpha(1B)-AR(-/-), and alpha 1D-AR(-/-) mice. Strikingly, responses to phenylephrine and noradrenaline were almost completely abolished in alpha(1A)-AR(-/-) mice. In contrast, the nonadrenergic agonist AVP produced dose-dependent vasoconstrictor responses that did not differ between any of the mouse genotypes tested. CONCLUSIONS. These findings provide evidence that the alpha(1A)-AR subtype mediates adrenergic vasoconstriction in murine ophthalmic arteries. (Invest Ophthalmol Vis Sci. 2011;52:4795-4799) DOI:10.1167/iovs.11-7516
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