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Differential roles for α 1 ‐ versus α 2 ‐ adrenoreceptor activation of mouse mesenteric arterial networks in vivo
Author(s) -
Westcott Erika Boerman,
Segal Steven S
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.853.11
Subject(s) - prazosin , phenylephrine , vasomotor , in vivo , rauwolscine , endocrinology , vasoconstriction , vasodilation , medicine , chemistry , antagonist , agonist , mesenteric arteries , propranolol , biology , receptor , blood pressure , artery , microbiology and biotechnology
Isolated segments of mesenteric arteries (MA) are studied widely to define mechanisms of vasomotor control yet little is known of their regulation in vivo. Smooth muscle tone in isolated MA often is induced through adrenoreceptor (AR) activation to study vasodilation; however, the AR subtype distribution in MA networks governing vasomotor tone in vivo is undefined. We tested the hypothesis that α 1 AR and α 2 AR differentially effect vasomotor tone in first‐, second‐ and third‐order (1A, 2A and 3A) MA in vivo. In anesthetized female C57BL/6 mice (4 – 6 mo), a MA network was exteriorized and superfused (~5 ml/min; pH 7.4, 37 ºC). Resting diameters (μm) were: 1A, 208 ± 26; 2A, 179 ± 19; 3A, 152 ± 22 and with 10 μM sodium nitroprusside were 219 ± 19, 204 ± 19 & 159 ± 15 (P>0.05; n = 4 – 8, means ± SE). In the presence of propranolol (βAR antagonist, 100 nM), norepinephrine (NE, 1 nM – 10 μM) constricted 1A, 2A and 3A by 51 ± 4, 53 ± 2 & 51 ± 5% (EC 50 = 288, 225 and 270 nM). Adding prazosin (α 1 AR antagonist, 10 nM) reduced NE constrictions to 13 ± 3, 11 ± 1 & 8 ± 2% (P<0.05) while rauwolscine (α 2 AR antagonist, 100 nM) had relatively little effect. Phenylephrine (α 1 AR agonist) constricted 1A, 2A & 3A by 51, 55 & 47% (EC 50 = 210, 180 and 160 nM) while UK 14,304 (α 2 AR agonist) constricted vessels by 14, 14 & 17% (EC 50 = 60, 85 and 193 nM). Thus, vasomotor tone results primarily through activation of α 1 ARs throughout MA networks in mice. (Support: NIH R01HL086483, R37HL041026)