Effect of Ca sup 2+ on Cl sup minus transport in thin ascending limb of Henle's loop

Journal Article · Mon Feb 01 00:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6945580

Kondo, Yoshiaki; Yoshitomi, Koji; Imai, Masashi ^[1]

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1. National Cardiovascular, Osaka (Japan)

Effects of ambient Ca{sup 2+} concentration on Cl{sup {minus}} transport across the thin ascending limb of Henle's loop (TAL) were examined by the in vitro microperfusion technique. When Ca{sup 2+} concentration in the bathing fluid was decreased from 1.5 mM to nominally 0 mM at 37{degree}C, the relative permeability of Cl{sup {minus}} to Na{sup +} (P{sub Cl}/P{sub Na}) estimated from the NaCl diffusion voltage changed from 2.44 to 1.27. When Ca{sup 2+} concentration of the luminal fluid was reduced, P{sub Cl}/P{sub Na} was unchanged. When Ca{sup 2+} concentration in the bathing fluid was change from 4.5 to nominally 0 mM, the lumen-to-bath flux coefficient for {sup 36}Cl (K{sub 1{yields}b}{sup 36Cl}) was decreased, whereas the value of {sup 22}Na was unchanged, indicating that the reduction of Ca{sup 2+} concentration in the bathing fluid selectively inhibits Cl{sup {minus}} transport without affecting Na{sup +} transport. The pH titration curves of relative Cl{sup {minus}} permeability examined at three different Ca{sup 2+} concentrations at 37{degree}C revealed that the interaction between proton and Ca{sup +} was noncompetitive. Addition of quin 2-AM, which reduced intracellular Ca{sup 2+} concentration, to the bath caused an irreversible suppression of Cl{sup {minus}} permeability, suggesting that the decrease in intracellular Ca{sup 2+} concentration also inhibits the Cl{sup {minus}} transport across the TAL. From these observations the authors suggest: (1) Cl{sup {minus}} transport across the TAL is regulated by Ca{sup 2+} preferentially on the basolateral membrane; (2) this regulation depends on temperature; and (3) there is a noncompetitive interaction between Ca{sup 2+} and proton in the regulation of the conductive Cl{sup {minus}} pathway.

• OSTI ID: 6945580
• Journal Information: American Journal of Physiology; (USA), Vol. 254:2; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CALCIUM COMPOUNDS
BIOLOGICAL EFFECTS
CHLORINE 36
MEMBRANE TRANSPORT
KIDNEYS
PHYSIOLOGY
SODIUM 22
PERMEABILITY
SODIUM CHLORIDES
TEMPERATURE DEPENDENCE
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CHLORIDES
CHLORINE COMPOUNDS
CHLORINE ISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HALIDES
HALOGEN COMPOUNDS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANS
RADIOISOTOPES
SODIUM COMPOUNDS
SODIUM ISOTOPES
YEARS LIVING RADIOISOTOPES
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