Effects of hypercholesterolemia on the microsomal membrane fluidity of intimal-medial versus medial layers of swine aorta: implications for the pathogenesis of vasospasm.
The hypothesis was examined that hypercholesterolemia induces a decrease in arterial microsomal membrane fluidity. To investigate this hypothesis, the fluorescence anisotropy (r) of 1,6-diphenylhexa-1,3,5-triene was measured in aortic microsomes isolated from the intimal-medial (IM) and medial (M) layers of swine thoracic aortas. After 10 weeks of feeding a high fat (10% lard) diet, serum cholesterol increased 2.3-fold compared to 3.6-fold in pigs fed a similar diet supplemented with 2% cholesterol. Based upon differences in r, the membrane fluidity of the IM layer was significantly less than the M layers. The membrane fluidity of the IM layer was inversely related to the severity of hypercholesterolemia regardless of dietary treatment. There were no differences in membrane fluidity among the three dissected M layers and the membrane fluidity of these layers was refractory to changes in serum cholesterol. A decrease in the membrane fluidity of the IM layer may contribute to the abnormal regulation of vascular tone which underlies the development of vasospasm in atherosclerotic arteries.
D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology / Q000648:ultrastructure*; D001161:Arteriosclerosis / Q000473:pathology / Q000503:physiopathology*; D001835:Body Weight; D002784:Cholesterol / Q000097:blood; D002791:Cholesterol, Dietary / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D005454:Fluorescence Polarization; D006937:Hypercholesterolemia / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008560:Membrane Fluidity; D008861:Microsomes / Q000502:physiology / Q000648:ultrastructure*; D009131:Muscle, Smooth, Vascular / Q000648:ultrastructure; D013552:Swine; D014666:Vasomotor System / Q000503:physiopathology
D002791:Cholesterol, Dietary; D004041:Dietary Fats; D002784:Cholesterol