Enhanced stretch-induced myogenic tone in the basilar artery of spontaneously hypertensive rats.
We investigated if the magnitude of myogenic tone in the basilar artery of SHR differs from that in WKY and, if so, whether RhoA- or PKC-dependent mechanisms were involved. Myogenic tone was developed in response to stretch. Stretch-induced myogenic contraction was significantly greater in the SHR than WKY in the presence of external Ca(2+). However, in the absence of external Ca(2+), stretch did not evoke a myogenic tone. The [Ca(2+)](i)-induced contraction was larger in SHR than WKY and the [Ca(2+)](i)-force curve was significantly shifted to the left in SHR compared to WKY. Y-27632 significantly inhibited stretch-induced myogenic tone, but the inhibitory effect was larger in the SHR than WKY. However, PKC inhibitors had no significant effect on the myogenic tone. RhoA and PKCepsilon were expressed at higher levels in the SHR compared to the WKY. RhoA and PKCalpha translocated from the cytosol to the cell membrane in response to stretch in both animals, but PKCepsilon was translocated only in SHR. Our results strongly suggest that stretch-induced myogenic tone is enhanced in SHR, and the activation of RhoA/Rho kinase plays an important role in the enhanced myogenic tone in SHR.
Ahn
Duck-Sun
DS
Department of Physiology, College of Medicine, Yonsei University, Seoul, South Korea.
Choi
Soo-Kyoung
SK
Kim
Young-Hwan
YH
Cho
Young-Eun
YE
Shin
Heung Mook
HM
Morgan
Kathleen G
KG
Lee
Young-Ho
YH
D000577:Amides / Q000494:pharmacology; D000818:Animals; D017704:Baroreflex; D001488:Basilar Artery / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D002118:Calcium / Q000378:metabolism; D004195:Disease Models, Animal; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D011311:Pressoreceptors / Q000378:metabolism / Q000503:physiopathology*; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014661:Vasoconstriction / Q000187:drug effects; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000577:Amides; D047908:Intracellular Signaling Peptides and Proteins; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D020742:rhoA GTP-Binding Protein; D002118:Calcium