PMID: 9430766Feb 7, 1998Paper

Functional characterization of post-junctional adrenergic receptor subtypes in bovine intra-mammary arteries

Journal of Veterinary Pharmacology and Therapeutics
F J Pereira, J A Will

Abstract

We examined the functional role of adrenergic receptor subtypes (ARs) in bovine intra-mammary arteries (IMAs), 1.5-2.5 mm internal diameter. Norepinephrine (NE) and phenylephrine (PE) produced concentration-dependent increases in tone in segments maintained at a previously determined optimal basal tension in vitro. The sensitivity of the tissue to NE and PE, based on -log molar ED50s was 6.87 +/- 0.17 and 7.05 +/- 0.35, respectively. In addition a Schild analysis yielded antagonist affinities for the receptor mediating contractile responses to NE (pA2 value) of 10.46 +/- 0.85 for prazosin and 6.29 +/- 0.18 for yohimbine. These data indicate a dominance of functional alpha 1 (alpha(1)) over alpha 2 (alpha(2))-ARS in this tissue. Based on the inhibitory effects of chloroethylclonidine (CEC) on PE responses and the further reduction in sensitivity when nifedipine was added to the CEC, also in the presence of PE, we conclude that there is more than one alpha(1)-AR subtype, with a predominant role for alpha(1B)-ARs in phenylephrine responses. Stimulation of beta (beta)-ARs, resulted in relatively small reductions in tone (the highest magnitude of response was 25.94 +/- 6.46% of the papaverine maximum at 3 x 10(-6) M isoproterenol); ...Continue Reading

Citations

May 20, 2003·Biochemical Pharmacology·Iain F GowMartin Wait
Oct 21, 2016·Indian Journal of Pharmacology·Ipsita MohantySubas Chandra Parija

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