title: Functional role of α1-adrenoceptor subtypes in murine ophthalmic arteries.
abstract: OBJECTIVE
  To identify the α(1)-adrenoceptor (α(1)-AR) subtypes mediating vascular adrenergic responses in murine ophthalmic arteries.
  
  
  METHODS
  Expression of mRNA was quantified for individual α(1)-AR subtypes in murine ophthalmic arteries using real-time PCR. To assess the functional relevance of α(1)-ARs for mediating vascular responses, ophthalmic arteries from mice deficient in one of the three α(1)-AR subtypes (α(1A)-AR(-/-), α(1B)-AR(-/-), and α(1D)-AR(-/-), respectively) and wild-type controls were isolated, cannulated with micropipettes, and pressurized. Changes in luminal artery diameter in response to the α(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 α(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, α(1B)-AR(-/-), and α(1D)-AR(-/-) mice. Strikingly, responses to phenylephrine and noradrenaline were almost completely abolished in α(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 α(1A)-AR subtype mediates adrenergic vasoconstriction in murine ophthalmic arteries.
authors: Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz, Mainz, Germany. adrian.gericke@gmx.net
authors: Adrian
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