Cellular distribution of GPR14 and the positive inotropic role of urotensin II in the myocardium in adult rat.
Urotensin II is a cyclic neuropeptide recently shown to play a role via its receptor GPR14 in regulating vascular tone in the mammalian cardiovascular system. The existence of GPR14 in rat heart has been validated by ligand binding assay and RT-PCR. In the present study, we investigated the cellular distribution of GPR14 protein in rat heart by using immunohistochemistry and confocal microscopic immunofluorescence double staining with antipeptide polyclonal antibodies against GPR14 and cell type markers for myocytes and endothelial cells. The direct effect of urotensin II on left ventricular contractility was further evaluated in isolated left ventricular papillary muscles of the rat. In paraffin-embedded heart sections, positive immunohistochemical staining was observed in the left ventricle but not in the right ventricle and atria. Immunofluorescence double staining revealed the cardiac myocyte as the only cell type expressing GPR14 protein in frozen heart sections as well as in isolated cardiac myocytes. There was no visible signal for GPR14 in intramyocardial coronary arteries and capillaries. The existence of GPR14 protein in rat heart was further validated by immunoprecipitation and Western blot analysis. In isolated rat left ventricular papillary muscle preparations, urotensin II induced an increase in active contractile force. GPR14 mRNA was also detected in rat heart by RT-PCR. These data provide the first direct evidence for the cellular localization of GPR14 receptor protein and a positive inotropic effect of urotensin II in normal rat heart.
Dept. of Physiology and Pathophysiology, Key Laboratory of Molecular Medicine of The Ministry of Education, Fudan University Shanghai Medical College, Shanghai 200032, People's Republic of China.
Hui
H
Gong
Yan-Xia
YX
Wang
Yi-Zhun
YZ
Zhu
Wen-Wei
WW
Wang
Ming-Jie
MJ
Wang
Tai
T
Yao
Yi-Chun
YC
Zhu
D000367:Age Factors; D000818:Animals; D015153:Blotting, Western; D007150:Immunohistochemistry; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D010210:Papillary Muscles / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014579:Urotensins / Q000494:pharmacology*; D016277:Ventricular Function, Left / Q000502:physiology
D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D014579:Urotensins; C473142:Uts2r protein, rat; C029677:urotensin II