K+ transport and membrane potentials in isolated rat parotid acini

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Am. J. Physiol.; (United States)

OSTI ID:6600151

Nauntofte, B; Dissing, S

42K+ transport properties of isolated rat parotid acini were characterized concomitant with measurements of membrane potentials (Em) by means of the fluorescent dye diSC3-(5). In unstimulated acini suspended in a 5 mM K+ buffer, Em was governed by the K+ and Cl- gradients and amounted to about -59 mV, a value that remained unaffected on cholinergic stimulation. In unstimulated acini, 42K+ influx was largely mediated by the Na+-K+ pump, and the residual influxes were mediated by a bumetanide-sensitive component (cotransport system) and by K+ channels. Efflux of 42K+ was largely mediated by a bumetanide-sensitive component and by K+ channels. In the unstimulated state, the cotransport system was mediating K+-K+ exchange without contributing to the net uptake of K+. Within 10 s after stimulation, a approximately 10-fold increase in the acinar K+ conductance (gK) occurred, resulting in a rapid net efflux of K+ that amounted to approximately 3.8 mmol.l cells-1.s-1. Measurements of 42K+ fluxes as a function of the external K+ concentration revealed that in the stimulated state gK increases when external K+ is raised from 0.7 to 10 mM, consistent with an activation of acinar gK by the binding of external K+ to the channel. 42K+ flux ratios as well as the effect of the K+ channel inhibitor from scorpion venom (LQV) suggest that approximately 90% of K+ transport in the stimulated state is mediated by ''maxi'' K+ channels.

• Research Organization: Univ. of Copenhagen (Denmark)
• OSTI ID: 6600151
• Journal Information: Am. J. Physiol.; (United States), Vol. 255
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
POTASSIUM COMPOUNDS
MEMBRANE TRANSPORT
BIOCHEMICAL REACTION KINETICS
CALCIUM 45
CELL MEMBRANES
FLUORESCENCE
OUABAIN
RATS
TRACER TECHNIQUES
VALINOMYCIN
ALKALI METAL COMPOUNDS
ALKALINE EARTH ISOTOPES
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DRUGS
EVEN-ODD NUCLEI
GLYCOSIDES
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LUMINESCENCE
MAMMALS
MEMBRANES
NUCLEI
ORGANIC COMPOUNDS
RADIOISOTOPES
REACTION KINETICS
RODENTS
STROPHANTHINS
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques