[Free fatty acids as inhibitors of the respiratory chain in testicular homogenates].
The supernatants of the 440 000 . g . min centrifugation of homogenates of rat, bull and boar testicles and sperm inhibit the NADH-oxidase activity of non-phosphorylating submitochondrial particles (ETP). Whereas no inhibitory activity was observed with young rats (150 g), a marked inhibition was detected with heavier animals. The inhibitory activity of testicles was located in the microsomal fraction. The reaction of the testicular inhibitor with the ETP is initiated by an instant reversible binding followed by a slow irreversible inhibition of the electron transport. The reason of the time-dependence is neither an interaction between the enzymes of the ETP and those of the microsomal electron transport nor a slow degradation of the ETP by microsomal phospholipases. Some observations indicate an indirect involvement of phospholipase via the formation of free fatty acids (FFA). The inhibitory fraction could be solubilized from the microsomes both by sodium cholate treatment and by ethanol extraction. After separation of the lipid classes by chromatography on silica gel and gas-chromatographic analysis the inhibitory fraction was identified as a mixture of free fatty acids (FFA) of different chain lengths and degree of saturation. Thus a new effect of FFA on the mitochondrial electron transport has been detected which is different from other actions known up till now. The degradation of the phospholipids of the endoplasmic reticulum in the spermatozoa may be the source of the enhanced formation of FFA. An inhibition of the cell respiration presumably does not occur in vivo. The high FFA level in the testicular homogenates of sexually mature animals is a consequence of an intensive FFA metabolism, especially of high phospholipase activity.
D000818:Animals; D002417:Cattle; D004579:Electron Transport; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D010740:Phospholipases / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D013045:Species Specificity; D013367:Submitochondrial Particles / Q000378:metabolism*; D013552:Swine; D013737:Testis / Q000378:metabolism*
D005230:Fatty Acids, Nonesterified; D010743:Phospholipids; D009245:NADH Dehydrogenase; D010740:Phospholipases
Unveresterte Fettsäuren als Hemmstoffe der Atmungskette in Hodenhomogenaten.