THE EFFECTS OF HYPERCHOLESTEROLAEMIC PLASMA ON VASCULAR SENSITIVITY TO NORADRENALINE

Abstract

1 The pressor responses to injected noradrenaline (NA) of 42 isolated perfused femoral arteries of the rabbit were studied. 2 Potentiation of the responses was found when hypercholesterolaemic plasma was perfused through the arteries. No change was found with normal plasma. 3 Potentiation of the responses was found when isolated β-lipoprotein in Krebs solution was perfused. No change was found with similar amounts of bovine albumen. 4 Pure cholesterol dissolved directly into normal plasma, and dissolved via propanol into Krebs solution or plasma caused no potentiation. Propanol alone in Krebs or plasma had no effect. 5 Potentiation was caused by a decreased equilibrium coefficient (K_eq) for the NA-adrenoceptor interaction and an increased maximal pressor response (R_max). 6 It is concluded that cholesterol carried on its apoprotein is capable of potentiating the pressor effects of noradrenaline.