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Characterization of Myogenic Factors in Normal Rat Mesenteric Veins
Author(s) -
Enouri Saad Salama,
Johnson Ron
Publication year - 2009
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.23.1_supplement.641.5
Subject(s) - myogenic contraction , vasodilation , medicine , vasoconstriction , arteriole , endocrinology , chemistry , microcirculation , electrical impedance myography , mesenteric arteries , vascular smooth muscle , chelerythrine , anatomy , protein kinase c , artery , biochemistry , kinase , smooth muscle
Vascular tone is maintained by the sympathetics, other neurohormones and myogenic factors. Myogenic factors have been characterized in arteries; however limited studies have been completed in veins. The objective of this study was to evaluate the contribution of myogenic factors to vascular tone in a large capacitance bed, the mesenteric veins, of normal male rats. Pressure myography was used to study isolated cannulated third order mesenteric venules (2‐12 mmHg) and arterioles (20‐140 mmHg). Arterioles showed myogenic contractions to pressure increases beginning at 60 mmHg, while venules showed evidence of myogenic tone (resistance to stretch) but not myogenic contractions. The contribution of endothelial dilators (N‐nitro‐L‐argentine, 100 µM) to net tone with increasing luminal pressure was minimal in both vessel types. The L‐type calcium channel blocker, Nifedipine (1 µM), abolished myogenic contributions to net tone in arterioles while only partially reducing responses in venules. The protein kinase C inhibitor (PKC), Chelerythrine (2.5 µM), also abolished myogenic contributions to net tone in arterioles; however, responses in venules were only substantially reduced. These findings suggest that in mesenteric venules (1) myogenic factors contribute to net venous tone and (2) myogenic tone is due in part to extracellular calcium and PKC activation and not altered by endothelial nitric oxide release. Grant Funding Source NSERC