Spontaneous and renal hypertensive rats: responsiveness of isolated right and left atria to noradrenaline, isoprenaline and methoxamine

Abstract The adrenergic responsiveness of right and left atria isolated from spontaneously hypertensive rats (SHR) and renal hypertensive rats (RHR) was studied. Right atria isolated from SHR showed subsensitivity to the chronotropic effect of noradrenaline (21.3-fold at the EC 50 level, P P P > 0.05) in sensitivity to the chronotropic effect of noradrenaline or isoprenaline. Chronotropic responsiveness to theophyline was not altered in right atria isolated from SHR or RHR. α 1 -Mediated inotropic responses to noradrenaline and methoxamine were blunted in left atria isolated from SHR. Left atria isolated from RHR showed supersensitivity to the inotropic effect of noradrenaline (5.4-fold at the EC 50 level, P P