title: Tyrosine kinase inhibition attenuates vasopressin-induced contraction of mesenteric resistance arteries: alterations in spontaneously hypertensive rats.
abstract: This study examined the role of tyrosine kinase-dependent signaling pathways in arginine vasopressin (AVP)-induced contractile responses in resistance arteries from spontaneously hypertensive rats (SHR). Systolic blood pressure was measured in conscious 6- and 21-week old SHR and Wistar Kyoto rats (WKY) by tail cuff measurements. Segments of third-order mesenteric arteries (about 200 microm in diameter, 2mm in length) were mounted in a pressurized chamber with the intraluminal pressure maintained at 45 mmHg. Contractile effects of AVP (10-12 to 10-7 mol/l) were determined in the absence and presence of the selective tyrosine kinase inhibitor tyrphostin A23 (10-5 mol/l) and the inactive analogue, tyrphostin A1 (10-5 mol/l). Systolic blood pressure was significantly higher in SHR compared with age-matched WKY (p < 0.01). AVP increased contraction in a dose-dependent manner with significantly greater responses in adult SHR (pD2 = 10.3 +/- 0.06) than age-matched WKY (pD2 = 9.4 +/- 0.04). Tyrphostin A23 shifted the AVP dose response curve to the right in 6- and 21-week WKY and 6-week SHR, but had little effect on AVP-induced responses in 21-week-old SHR. Tyrphostin A1 did not influence contraction in any groups. Protein tyrosine phosphorylation in VSMCs and mesenteric arteries was increased 2-3 fold in 21-week SHR compared with WKY counterparts. AVP significantly increased tyrosine phosphorylation in VSMCs, with enhanced effects in SHR compared with WKY (p < 0.05). These effects were inhibited by tyrphostin A23. Our findings demonstrate that protein tyrosine kinases contribute to AVP-induced contraction of resistance arteries from WKY and SHR during the phase of developing hypertension. These processes do not seem to play an important role in AVP-induced hypercontractility in SHR with established hypertension.
authors.affiliation: Multidisciplinary Research Group on hypertension, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec, Canada.
authors.forename: Dierk
authors.initials: D
authors.lastname: Endemann
authors.forename: Rhian M
authors.initials: RM
authors.lastname: Touyz
authors.forename: Guoying
authors.initials: G
authors.lastname: Yao
authors.forename: Ernesto L
authors.initials: EL
authors.lastname: Schiffrin
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000201:enzymology*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014655:Vascular Resistance / Q000187:drug effects* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D014667:Vasopressins; D011505:Protein-Tyrosine Kinases