Hypophysectomy and adrenalectomy decrease Ca2+-induced swelling of rat liver mitochondria.

Hypophysectomized rats showed significant modifications in Ca2+-induced swelling and MgATP-induced contraction of liver mitochondria. Two-three months after operation, maximal swelling (MS), rate of swelling (VS), maximal contraction (MC) and rate of contraction (VC) were decreased by 77 (MS), 83 (VS), 79 (MC) and 62 (VC) % (in all cases P less than 0.05 as compared with normal rat mitochondria). Treatment of hypophysectomized rats with bovine pituitary extract, for two weeks, counteracted the effect of hypophysectomy, whereas treatment with bovine growth hormone was ineffective. Adrenalectomy produced similar though less extensive modification of Ca2+-induced swelling but failed to affect the MgATP-dependent mitochondrial contraction. Substrate oxidation by hypophysectomized or adrenalectomized rat mitochondria showed no modification of the energy-yielding mechanisms, capable of explaining the observed changes in mitochondrial swelling.