Mechanisms of Ca uptake in high K/low Na solutions

Conference · Tue Mar 04 23:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7189595

Lodge, N J; Gelband, H

Ca uptake into neonatal rat atrium was measured with /sup 45/Ca. Extracellular /sup 45/Ca was displaced by washing tissues (45 min) in ice-cold Tyrode's containing 6.8 mM Ca/5 mM EGTA. Unless otherwise stated, solutions were pH balanced with HCO/sub 3//PO/sub 4//CO/sub 2/. Solutions in which 129 mM K or choline were substituted for 129 mM Na significantly stimulated Ca uptake (p < 0.001 for both). Inhibition of the Na/K pump (0 mM K solution), to increase intracellular Na, increased subsequent Ca uptakes measured in control, choline/low Na and high K/low Na solutions. The choline/low Na-stimulated uptake was increased by 104% while the high K/low Na stimulated uptake was increased only 11%. Cadmium (0.01-10 mM) blockade of the choline/low Na and high K/low Na uptakes was tested. Hepes buffered (HCO/sub 3//PO/sub 4//CO/sub 2/-free) solutions were used to avoid precipitation of Cd salts. The high K/low Na (Hepes) uptake was significantly (p < 0.001) greater than control and was 50% inhibited by 0.3 mM Cd. Choline/low Na in Hepes buffer increased Ca uptake only 5.1 +/- 4.3 ..mu..mol/kg (n=22) above control. In separate experiments, the choline/low Na (Hepes)-stimulated uptake (12.8 +/- 4.3 ..mu..mol/kg, n=8) was increased to 29.3 +/- 4.7 ..mu..mol/kg (n=8) by the addition of 1.8 mM PO/sub 4/. This intervention reduced the high K/low Na (Hepes)-stimulated uptake (47.1 +/- 6.4 ..mu..mol/kg, n=8) to 33.8 +/- 4.5 ..mu..mol/kg (n=8). They hypothesize that the uptake of Ca, induced by solutions of elevated K and lowered Na, is mediated by a minimum of two mechanisms; one stimulated by PO/sub 4/ and sensitive to transmembrane ion gradients, the other reduced by PO/sub 4/ and relatively insensitive to ion gradients.

• Research Organization: Univ. of Miami School of Medicine, FL
• OSTI ID: 7189595
• Report Number(s): CONF-8604222-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:4; ISSN FEPRA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALCOHOLS
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CADMIUM
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
CHOLINE
DAYS LIVING RADIOISOTOPES
DRUGS
ELEMENTS
EVEN-ODD NUCLEI
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LIPOTROPIC FACTORS
MAMMALS
MEMBRANE TRANSPORT
METALS
NEONATES
NUCLEI
ORGANIC COMPOUNDS
POTASSIUM
QUATERNARY COMPOUNDS
RADIOISOTOPES
RATS
RESPONSE MODIFYING FACTORS
RODENTS
SODIUM
TRACER TECHNIQUES
UPTAKE
VERTEBRATES