title: Inhibition of Rho-kinase in the brainstem augments baroreflex control of heart rate in rats.
abstract: The Rho/Rho-kinase pathway in the nucleus tractus solitarii (NTS) of the brain stem contributes to blood pressure regulation. Activation of this pathway might be involved in the central nervous system mechanisms of hypertension. The aim of the present study was to determine whether baroreflex control of heart rate is altered by inhibition of Rho-kinase in the NTS. Adenovirus vectors encoding dominant-negative Rho-kinase or beta-galactosidase were transfected into the nucleus tractus solitarii of Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Baroreflex control of heart rate was examined by changing arterial pressure with an intravenous infusion of phenylephrine or sodium nitroprusside. The maximum gain of baroreflex control of heart rate was attenuated in SHR compared with WKY before the gene transfer. Transfection of adenovirus vectors encoding dominant-negative Rho-kinase significantly augmented the maximum gain in both WKY and SHR. The extent of this augmentation, however, was greater in SHR than in WKY. After treatment with metoprolol, the maximum gain was significantly decreased in rats transfected with adenovirus vectors encoding dominant-negative Rho-kinase, but not in nontransfected rats. In contrast, after treatment with atropine, the maximum gain was greater in rats transfected with adenovirus vectors encoding dominant-negative Rho-kinase compared with nontransfected rats, although it was decreased in both groups. These results suggest that inhibition of Rho-kinase in the NTS augments baroreflex control of heart rate, in both WKY and SHR, probably because of a cardiac sympathoinhibitory effect.
authors.affiliation: Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Ito
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hirooka
authors.forename: Yoji
authors.initials: Y
authors.lastname: Sagara
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Kimura
authors.forename: Kozo
authors.initials: K
authors.lastname: Kaibuchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Shimokawa
authors.forename: Akira
authors.initials: A
authors.lastname: Takeshita
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
mesh_terms: D000256:Adenoviridae; D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D001933:Brain Stem / Q000201:enzymology*; D005822:Genetic Vectors; D006339:Heart Rate / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014162:Transfection; D001616:beta-Galactosidase / Q000235:genetics; D054460:rho-Associated Kinases
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D001616:beta-Galactosidase