Contribution of renal medullary mitochondrial density to urinary concentrating ability in mammals

STETSON. Contribution of renal medullary mitochondrial density to urinary concentrating ability in mammals. Am. J. Physiol. 261 (Regulatory Integrative Comp. Physiol. 30): R719-R726, 1991.-In mammals, the length of the loops of Henle increases with increasing body size without a concomitant rise in urinary concentrating ability. Because mass-specific metabolic rate falls with increasing body mass, this study sought to determine the extent to which this decline in metabolic rate could explain the low urinary concentrating ability of large mammals with long loops of Henle. Mitochondrial ultrastructural parameters were measured in the medullary thick ascending limbs (mTALs) of a series of nine mammalian genera ranging in body mass from 0.011 kg (bats) to-400 kg (horses). The volume of mitochondria as a percent of mTAL cellular volume declined with increasing body mass ( Mb-“.056). Inner mitochondrial mem