Focal alterations in metabolic capabilities associated with development of cholesterol-induced atheromatous lesions: a quantitative cytochemical study

Cytochemical correlates of atherosclerosis-resistant and susceptible lesions of the normal rabbit aorta

Quantitative cytochemical and microfluorimetric techniques were employed to compare mural intermediary metabolism--endothelial macromolecular uptake changes in spontaneous aortic-arteriosclerotic lesions of normolipemic New Zealand White rabbits. Specifically, mural succinic (SDH), lactic (LDH), and glucose-6-phosphate (G-6-PDH) dehydrogenase activities and luminal surface uptake of fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) were measured in lesion sites abnormally resistant (calcified) and susceptible (proliferative) to dietary hypercholesterolemia. Calcified lesions exhibited severe (55-66%) diminution of SDH, LDH, and G-6-PDH activities within the involved inner mural zone and a comparable (68%) decline in luminal FITC-BSA uptake. Concomitant reductions in FITC-BSA uptake (30%) and marker enzymes of the predominant energy transducing pathways in arterial tissue, i.e., SDH (30%) and LDH (31%), were evidenced in proliferative foci, whereas G-6-PDH was augmented (52%) in comparison to nonlesioned aortic segments. These data lend additional support to the concept that endothelial uptake of plasma-borne macromolecules is coupled to oxidizable substrate requirements of inner avascular compartments of the arterial wall. It is postulated that diminished macromolecular transport in these degenerative lesions stems from reduced mural metabolic demands, and that pharmacologic reduction of vascular smooth muscle metabolism may depress uptake of sclerogenic macromolecules.

Scanning-integrating cytophotometric analyses of brain neuronal RNA and acetylcholinesterase in acute soman toxicated rats

Cytophotometric analyses of RNA and acetylcholinesterase responses of caudate and cerebrocortical neurons of soman toxicated rats were conducted to characterize impairments in regulatory aspects of neuronal metabolism occurring in the acute phase of cholinesterase impairment. There was a severe and dose-dependent suppression (20-60%) in neuronal acetylcholinesterase activity in both a.m. and p.m.-treated rats; no diurnal differences were apparent in control acetylcholinesterase levels or neuronal acetylcholinesterase responsiveness to soman toxication. RNA levels, however, were markedly higher in p.m. than in a.m. saline-treated controls. Soman depressed caudate neuron RNA contents in the afternoon, but not in the morning. Cerebrocortical neuron RNA levels were suppressed in both a.m. and p.m.-toxicated rats, although this RNA depletion was more severe in the afternoon. These results indicate that soman can elicit marked alterations in neuronal transcriptional-translational capabilities and that there are diurnal variations in cellular metabolic responsiveness to soman toxication. Although functional relationships between soman-induced cholinesterase inhibition and RNA depletion remain to be elucidated, depressed RNA metabolism appears to be a maladaptive response preventing rapid regeneration of cholinesterase following poisoning.