Beta-adrenergic receptor (beta-AR)-mediated vasorelaxation declines with age in humans and animal models. This is not caused by changes in expression of beta-AR, G alpha s, adenylyl cyclase, or protein kinase A but is associated with decreased cAMP production. Expression and activity of G protein receptor kinase-2 (GRK-2), which phosphorylates and desensitizes the beta-AR, increases with age in...

Our previous study demonstrated the longer duration of action potential in ventricular myocytes from genetically diabetic WBN/Kob rats without change in calcium channel density compared with age-matched controls [Tsuchida, K., H. Watajima, and S. Otamo. Am. J. Physiol. 267 ( Heart Circ. Physiol. 36): H2280-H2289, 1994]. In the present study we examined the alteration of potassium currents, espe...