The Alteration Of Relaxation Of Different Subtypes Of β Adrenergic Receptor On Aorta From Spontaneously Hypertensive Rats And Wistar Rats Of Different Age

ObjectiveTo observe the effects of Isoprenaline(Iso),Dobutamine(Dob),Salbutamol(Sal), SR 58611A on phenylephrine-induced contraction of thoracic aorta rings isolated from SHR and Wistar rats aged 4 weeks and 12 weeks.MethodsThe effects of the drugs on rat isolated thoracic aortic rings were observed with PowerLab computer system.Results1.The relaxations to Iso(10^-8～10^-4mol/L) were progressive weakening with aging in SHRs and Wistar rats.2.The relaxation of Iso was shifted to the right and upward in the presence of Nadolol(10μM) 3.After endothelium removal,the response to Iso was partly inhibited in SHRs and Wistar rats,but was strongly inhibited in SHRs aged 12 weeks.Iso induced endothelium-independent relaxation was not modified in the presence of nadolol.3.In endothelium-denuded rings pretreated with pertussis toxin(PTX),Iso induced relaxation was partly restored in SHRs aged 12 weeks,but not modified in wistar rats.4.The relaxation to Dobutamine(10^-8～10^-4mol/L) were progressive weakening in SHRs but not in Wistar rats.5.The relaxation to Salbutamol(10^-8～10^-4mol/L) were progressive weakening with aging in SHRs and Wistar rats.6.The relaxation of SR 58611A was not modified in SHRs and wistar rats of different age.Conclusions The relaxation to different subtype ofβAR was changed differently with age and hypertension.The endothelium-independent component of the relaxation to Iso was impaired during age and hypertension.Gi protein overexperssion may be possible factors that contribute to this alteration in hypertension.