Studies on the effect of capsaicin on metabolic reactions of isolated rat liver mitochondria

Abstract

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) was found to inhibit the respiratory response of rat liver mitochondria, respiring in the presence of glutamate as substrate, to the additions of ADP(+P i ), 2,4-dinitrophenol(DNP), and CaCl 2 (+P i ). The inhibitory effect of capsaicin on mitochondrial oxidative phosphorylation can also be observed with other NAD-linked substrates such as β-hydroxybutyrate and malate plus pyruvate and was partially reversed by adding bovine serum albumin to the reaction mixtures. When the mitochondria were respiring with succinate as substrate, capsaicin was less effective in inhibiting state 3 and DNP-stimulated respiration but exerted an uncoupling action on mitochondrial respiration. This uncoupling effect was evident at the doses of capsaicin much higher than that required to depress oxidative phosphorylation when NAD-linked substrates were used. Capsaicin was also found to depress the DNP-activated adenosine triphosphatase (ATPase) activity of rat liver mitochondria. These results indicate that capsaicin has profound effect on the energy-linked functions of isolated mitochondria. © 1976.