Title: α1A-Adrenoceptors, but not α1B- or α1D-adrenoceptors, contribute to enhanced contractile response to phenylephrine in cooling conditions in the rat tail artery
Abstract: Cutaneous arteries show enhanced contraction in response to cooling, which is suggested to be mediated via α2C-adrenoceptors. We have previously shown that α1-adrenoceptors are also involved in the enhanced contraction in cooling conditions. In the present study, we aimed to identify the α1-adrenoceptor subtype involved in the response. Phenylephrine-induced contraction was enhanced by cooling to 24 °C in isolated rat tail arteries but suppressed in iliac arteries and aorta. At 37 °C, RS100329 (3 nM), an α1A-adrenoceptor antagonist, shifted the concentration-response curve of phenylephrine to the right in tail and iliac arteries, but not in aorta, while BMY7378 (10 nM), an α1D-adrenoceptor antagonist, shifted them to the right in aorta and iliac arteries, but not in tail arteries. At 24 °C, RS100329 (3 nM) shifted the concentration-response curve of phenylephrine to the right and decreased the maximum contraction in tail arteries. The inhibitory effects of RS100329 (3 nM) were more pronounced at 24 °C, compared to at 37 °C, implying larger contribution of α1A-adrenoceptors at 24 °C. In tail arteries, the maximum contraction of A-61603, an α1A-adrenoceptor agonist, was larger at 24 °C than at 37 °C. In contrast, in iliac arteries, the maximum contraction of A-61603 was smaller and its EC50 was smaller at 24 °C than at 37 °C. Under the condition where α1D-adrenoceptors were blocked, phenylephrine-induced contraction of iliac arteries was rather enhanced by cooling to 24 °C. These results suggest that α1A-adrenoceptors contribute to the enhanced contraction of cutaneous arteries in cooling conditions.
Publication Year: 2018
Publication Date: 2018-09-05
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 7
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