The Effects of Hypophysectomy on the Structure and Function of Rat Liver Mitochondria

Abstract

The effects of hypophysectomy on the oxidative functions and morphology of rat liver mitochondria were examined. The respiratory rate of mitochondria both in states 3 and 4 decreased with time after the operation. However, the respiratory control index and P:O ratio did not change appreciably. After hypophysectomy the respiratory cytochrome contents of isolated mitochondria decreased in parallel with decrease in respiratory activities, but the respiratory cytochrome contents of whole liver homogenates, though first decreasing markedly were later restored to almost normal levels. The microsomal cytochrome content also decreased but then gradually increased again from 9days after hypophysectomy. Electron microscopic observations on hepatocytes revealed that the mitochondrial number and volume per unit of cytoplasm increased after the operation, and the cytoplasm became almost completely filled with mitochondria. The rough surfaced endoplasmic reticulum appeared to surround each mitochondrion. Subsequent administration of growth hormone increased the cytochrome contents of both the mitochondria and microsomes.