Physiological significance of P2X receptor-mediated vasoconstriction in five different types of arteries in rats

Abstract

P2X 1 receptors, the major subtype of P2X receptors in the vascular smooth muscle, are essential for α,β-methylene adenosine 5′-triphosphate (α,β-MeATP)-induced vasoconstriction. However, relative physiological significance of P2X 1 receptor-regulated vasoconstriction in the different types of arteries in the rat is not clear as compared with α 1 -adrenoceptor-regulated vasoconstriction. In the present study, we found that vasoconstrictive responses to noncumulative administration of α,β-MeATP in the rat isolated mesenteric arteries were significantly smaller than those to single concentration administration of α,β-MeATP. Therefore, we firstly reported the characteristic of α,β-MeATP-regulated vasoconstrictions in rat tail, internal carotid, pulmonary, mesenteric arteries, and aorta using single concentration administration of α,β-MeATP. The rank order of maximal vasoconstrictions for α,β-MeATP (E max·α,β-MeATP ) was the same as that of maximal vasoconstrictions for noradrenaline (E max·NA ) in the internal carotid, pulmonary, mesenteric arteries, and aorta. Moreover, the value of (E max·α,β-MeATP /E max·KCl )/(E max·NA /E max·KCl ) was 0.4 in each of the four arteries, but it was 0.8 in the tail artery. In conclusion, P2X 1 receptor-mediated vasoconstrictions are equally important in rat internal carotid, pulmonary, mesenteric arteries, and aorta, but much greater in the tail artery, suggesting its special role in physiological function.

Exhaustive swimming differentially inhibits P2X1 receptor- and α1-adrenoceptor-mediated vasoconstriction in isolated rat arteries

“…Our recent study demonstrated that the maximal vasoconstriction mediated by P2X 1 receptors reached at least 40% of those mediated by α 1 -adrenoceptors in the rat internal carotid, mesenteric and pulmonary arteries. P2X 1 receptormediated vasoconstriction even reached 80% in the caudal artery [24] , which suggested that purinergic transmission can be useful to maintain the basal vascular tone and could be important to the hemodynamic control in rats subjected to exhaustive swimming exercise. Sugawara et al [41] also suggested that a reduction in α-adrenoceptor-mediated vascular tone contributes to improved arterial compliance in healthy adults who engage in endurance exercise.…”

“…A ring segment (4 mm long) without endothelium was mounted horizontally in a 10-mL organ bath, and the isometric tension was recorded by a polygraph (ERT-884, Youlin Electron Co, Kaifeng, China). Preloads were applied to the preparations of internal carotid artery (1.0 g), caudal artery (0.75 g), pulmonary artery (1.0 g), mesenteric artery (1.0 g), and aorta (2.0 g) [24] . The preparations were allowed to equilibrate for 1 h in K-H solution.…”

“…No significant differences in vasoconstrictive responsiveness between the preparations that were either exposed to a second administration of NA or to α,β-MeATP were observed, suggesting that the 5 types of arteries obtained from the SCG rats and the ESEG rats were comparable in the present study. Because the EC 50 values of KCl treatment were significantly greater in different types of arteries treated with α,β-MeATP than NA [24] , and the maximum vasoconstrictive response to KCl in the rat mesenteric and caudal arteries in the SCG were greater than the response in the ESEG, we expressed the vasoconstrictive responses to NA and α,β-MeATP as g/mg tissue. Concomitantly, we found the exhaustive swimming exercise did not alter the EC 50 values of KCl.…”

(−)Doxazosin is a necessary component for the hypotensive effect of (±)doxazosin during long-term administration in conscious rats

“…A ring segment (4 mm long) without the endo-www.chinaphar.com Zhao J et al Acta Pharmacologica Sinica npg thelium was mounted horizontally in a 10-mL organ bath by carefully inserting a tungsten wire through the lumen of the arterial ring preparation and anchoring it to a stationary support. Another similarly inserted tungsten wire was connected to an isometric tension transducer coupled to a polygraph (ERT-884, Youlin Electron Co, Kaifeng, China) [19] to record the change in tension of the preparation. A preload of 0.75 g was applied to the arterial ring preparations, and the preparations were allowed to equilibrate for 1 h in Krebs-Henseleit (K-H) solution with the following composition (mmol/L) [19,20] : NaCl 133, KCl 4.7, NaH 2 PO 4 1.35, NaHCO 3 16.3, MgSO 4 0.61, glucose 7.8, and CaCl 2 2.52 with a pH 7.4.…”

“…Another similarly inserted tungsten wire was connected to an isometric tension transducer coupled to a polygraph (ERT-884, Youlin Electron Co, Kaifeng, China) [19] to record the change in tension of the preparation. A preload of 0.75 g was applied to the arterial ring preparations, and the preparations were allowed to equilibrate for 1 h in Krebs-Henseleit (K-H) solution with the following composition (mmol/L) [19,20] : NaCl 133, KCl 4.7, NaH 2 PO 4 1.35, NaHCO 3 16.3, MgSO 4 0.61, glucose 7.8, and CaCl 2 2.52 with a pH 7.4. The K-H solution was maintained at 37 °C and aerated with 95% O 2 and 5% CO 2 .…”