The Distribution Characteristics Of α₁-adrenergic Receptor Subtypes In Rat Ureter

a1-adrenoceptors(a1-AR) is part of the clan of G-protein-coupled receptor and widely distributed in organs, tissues and cells of a organism Meanwhile, it mediates many physiology effects, such as urinary tract smooth muscle contraction, vasoconstriction, glycogenolysis and cardiac inotropic chronotropic effect. With the development of the pharmacology and the molecular biology techniques, the classification and distribution of a1-AR subtypes has progressively been a definite, which is of great use to clinical nedicine.Objective:The distribution characteristics of a1-adrenoceptors(a1-AR) subtypes in proximal,medial,and distal region of the rat ureter were investigated.Methods:The thesis adopted radioligand binding assay and employed GraphPad PRISM 5.01 software to analyze the data, so as to calculate the density of a1-AR subtypes. The data were all designated as x±s. The statistical analysis adopted t-test. Statistics processing adopted SPSS 11.5 software.Conclusion:Through the saturation test, we reached the result:The distribution of binding sites of a1-AR in the different regions of the rat ureter were non-uniform, the Bmax for Lower Ureteral was 14911±1253 fmol/mg, significantly higher than the proximal (9077±211 fmol/mg) and medial (9164±158 fmol/mg), whereas the difference of the distribution between the proximal and medial was not significant. After the CEC pre-incubation of the Crude membrane specimen, the maximum binding capacity Bmax of a1-AR and [125I]-HEAT decreased about 64%, compared with the control group. Competitive inhibition test results showed when When the high specificity antagonist of a1-AR subtypes (5-MU, Cyclazosin, BMY7378) were present, Bmax of a1-AR and [125I]-HEAT were decreased. Therefore, we drew the conclusion that a1-AR density in the distal ureter was more than the proximal and medial, While there was no difference between the Kd and Hill coefficients. A single point of competitive inhibition reaction showed that the existence of three kinds of a1-AR subtypes in the rat ureter, namely a1A, a1B and a1D-AR subtypes. In the meantime, a1D-AR subtypes and a1A-AR subtypes were significantly more than subtype, while the distribution of a1D-AR subtype was slightly more than subtype.