Reaction of Kidney Medullary Laminin to Prolonged Dehydration of Rats

Laminin is the main water-soluble protein in the basement membrane of epithelial tissue. The content of laminin in the renal parenchyma was studied in rats that were on an alternative water diet for 60 h with excessive water intake or a complete lack of drinking water in the food. It has been shown that the osmotic concentration of urine, which develops as a result of water deprivation, is accompanied by a quantitative change in the composition of laminin. It has been established that the amount of laminin beta chain increases in the kidney medulla of dehydrated rats. This effect is observed only in WAG rats with normally expressed vasopressin gene and is absent in mutant Brattleboro rats unable to synthesize the hormone. The increase in the level of beta-laminin also does not extend to the cortical substance. Based on the original and new data, it is assumed that laminin, as a key regulatory element in the basement membrane of the tubular epithelium, participates in the adaptive reaction of the concentrating system of the kidney to conditions of prolonged dehydration. Hyperhydration does not affect the level of laminin in the renal parenchyma.