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Juvenile growth reduces the influence of epithelial sodium channels on myogenic tone in skeletal muscle arterioles
Author(s) -
Kang Lori S,
Masilamani Shyama,
Boegehold Matthew A
Publication year - 2016
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/1440-1681.12664
Subject(s) - skeletal muscle , sodium channel , chemistry , myogenic contraction , tone (literature) , muscle tone , juvenile , endocrinology , sodium , medicine , biology , smooth muscle , physical medicine and rehabilitation , art , literature , organic chemistry , genetics
Summary Previous studies have documented that rapid juvenile growth is accompanied by functional changes in the arteriolar endothelium, but much less is known about functional changes in arteriolar smooth muscle over this period. In this study, we investigate the possible contribution of epithelial sodium channels ( EN aC) to the myogenic behaviour of arterioles at two stages of juvenile growth. The effects of the EN aC inhibitor benzamil on different levels of myogenic tone were studied in isolated gracilis muscle arterioles from rats aged 21‐28 days (“weanlings”) and 42‐49 days (“juveniles”). EN aC subunit expression in the arteriolar wall was also determined, and the interaction between EN aC and nitric oxide ( NO ) in regulating vascular tone was explored by combined use of benzamil and N G ‐monomethyl‐ l ‐arginine ( l ‐ NMMA ). At physiological pressures, both steady‐state myogenic tone and the dynamic adjustments in this tone triggered by acute pressure changes were less in juvenile arterioles than in weanling arterioles. α, β and γ EN aC protein was present in arterioles at both ages, but benzamil only had an effect on myogenic tone in weanling arterioles. In these vessels, benzamil increased, rather than decreased, myogenic tone, and this effect was prevented by l ‐ NMMA or endothelial removal. These findings suggest that although EN aC is present in gracilis muscle arterioles of both weanling and juvenile rats, it is not obligatory for the genesis of myogenic activity in these vessels at either age. However, EN aC activity can significantly modulate the level of myogenic tone through stimulation of endothelial NO release at an early stage of growth.