Relation of actin fibrils to energy metabolism of endothelial cells.
The physiological significance of the association of glycolytic enzymes with actin fibrils was investigated in cell culture. Cytochalasin D (CD) was used to induce the known actin-based sequence of events in a culture of an endothelial-cell line (XTH-2) derived from hearts from tadpoles of Xenopus laevis. 1 min following addition of CD, ruptures in the cortical fibrillar meshwork and in stress fibres are seen. At the same time the cellular ATP level decreases by ca. 25%. This and the following reactions resulting in a kind of arborization depend on a continuous supply with metabolic energy. As shown by measurements of oxygen consumption, cells with intact energy metabolism provide the ATP needed from glycolysis; ATP produced by oxidative phosphorylation is not utilized as long as lactate dehydrogenase (LDH) reoxidizes NADH2. After inhibition of LDH, respiration in XTH-2 cells doubles. CD treatment induces a transient increase in oxygen consumption, indicating an increased energy supply by respiration. From these results we conclude: The energy needed by the actomyosin system is - under normal metabolic conditions -supplied from ATP phosphorylated in glycolysis. The processes of energy metabolism seem to be highly compartmentalized; ATP is not a parameter that is kept constant in time intervals of minutes up to one hour.
D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002460:Cell Line; D015638:Cytochalasin D; D003572:Cytochalasins / Q000494:pharmacology; D004727:Endothelium / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects; D006651:Histocytochemistry; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects*; D013997:Time Factors; D014982:Xenopus laevis
D000199:Actins; D003572:Cytochalasins; D015638:Cytochalasin D; D000968:Antimycin A; D000255:Adenosine Triphosphate