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Increased myogenic responsiveness of skeletal muscle arterioles with juvenile growth
Author(s) -
Samora Julie Balch,
Frisbee Jefferson C,
Boegehold Matthew A
Publication year - 2007
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.21.5.a494-d
Subject(s) - weanling , myogenic contraction , juvenile , endocrinology , medicine , arteriole , skeletal muscle , biology , chemistry , anatomy , circulatory system , smooth muscle , genetics
In skeletal muscle of young animals, microvascular network growth is accompanied by changes in some local blood flow control mechanisms. We recently found that when pressurized to in vivo levels, isolated gracilis muscle arterioles from weanling rats (age 24–26 days) develop greater spontaneous tone than those from juvenile rats (46–48 days). To determine if this reflects greater smooth muscle myogenic activity in younger rats, diameters of gracilis muscle arterioles from weanling and juvenile rats were measured over luminal pressures of 40–140 mm Hg. At pressures above 100 mm Hg, the myogenic index (relative slope of the active pressure‐diameter curve) of juvenile arterioles was greater than that of weanling arterioles. Endothelial denudation significantly increased myogenic activity and active tension generation at lower pressures in juvenile arterioles, and reduced myogenic activity at higher pressures in weanling arterioles. The PGH 2 /TXA 2 receptor antagonist SQ29548 had no effect on myogenic activity of juvenile arterioles, but reduced myogenic activity of weanling arterioles at higher pressures. This suggests that endothelial PGH 2 /TXA 2 contributes to arteriolar myogenic behavior in young animals. Despite the eventual loss of this contribution, subsequent growth is accompanied by a modest increase in overall myogenic responsiveness. (NIH RO1 DK64668, AHA 0330194N, NIH HL 44012)