Electrolyte and water transport in the newt renal tubule due to the action of low-molecular fractions isolated from the intestine of the hibernating ground squirrel.
The micropuncture technique and X-ray microanalyses were used to evaluate Na, K, Ca, Mg, Cl and fluid transport in the early distal tubule mediated by low-molecular fractions isolated from the intestine of the hibernating ground squirrel (HSI). Perfusion of intertubular capillaries with a solution containing HSI with a molecular weight of 1-10 kD (0.1 mg.ml-1) decreased the relative reabsorption of fluid, Ca and Mg. The other low-molecular fraction 1-10 kD of m.v. (0.1 mg.ml-1) isolated from the intestine of alert ground squirrels (ASI 1-10) caused no significant changes of the ionic concentration and inulin concentration index in the distal tubule. Fraction 1 with molecular weight 1.2-4.5 kD (0.1 mg.ml-1) obtained by further division of HSI 1-10, decreased the reabsorption of fluid and ions under study. Fractions 2 (m.w. 0.98 kD) and 3 (m.w. 0.89 kD) had no effect on the ion and fluid transport in the same tubule. The addition of naloxone (0.4 mg.ml-1) blocked the action mediated by HSI 1-10 or fraction 1. Thus, the substance(s) capable of regulating Ca, Mg, and fluid transport in the distal tubule likely to be mediated by the opiate-dependent process has a molecular weight of 1.2-4.5 kD.
Goncharevskaya
O A
OA
Sechenov Institute of Evolutionary Physiology and Biochemistry, Leningrad, USSR.
Monin YuG
Kramarova
L I
LI
Kolaeva
S G
SG
D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000493:pharmacokinetics; D002457:Cell Extracts / Q000032:analysis / Q000494:pharmacology*; D002712:Chlorides / Q000493:pharmacokinetics; D004723:Endorphins / Q000502:physiology; D006605:Hibernation / Q000502:physiology; D007422:Intestines / Q000737:chemistry / Q000166:cytology* / Q000502:physiology; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology*; D008274:Magnesium / Q000493:pharmacokinetics; D008970:Molecular Weight; D009270:Naloxone / Q000494:pharmacology; D011188:Potassium / Q000493:pharmacokinetics; D012589:Sciuridae / Q000502:physiology*; D014319:Triturus / Q000502:physiology*; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
D002457:Cell Extracts; D002712:Chlorides; D004723:Endorphins; D009270:Naloxone; D008274:Magnesium; D011188:Potassium; D002118:Calcium