ISSN:
1432-2013
Keywords:
Salivary gland
;
Muscarinic receptor
;
Intracellular Ca
;
Intracellular ATP
;
Potassium current
;
Chloride current
;
Tetraethylammonium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract In freshly dispersed rat parotid acinar cells, 10 μM carbachol increased outward currents at 0 mV and also inward currents at −70 mV recorded with the whole-cell clamp method using patch pipettes containing 1 mM EGTA. When EGTA in the pipette was increased to 2.4 mM, carbachol increased only outward currents and a further increase of EGTA to 4 mM blocked the carbachol response. Effects of changes in external K+ and Cl− concentrations suggested that outward currents were carried by K+ and inward by Cl−. Effects of Ca2+ removal from the medium differed between experiments with 0 and 5 mM ATP in the patch pipettes. When pipettes contained no ATP, responses evoked by repeated applications of 10 μM carbachol (0.5–1 min) at 1.5–4 min intervals decreased only slowly after Ca2+ removal, outward currents being reduced to 90±6% and inward currents to 47±11% (n=6) in 10 min. On the other hand, when 5 mM ATP was included in the electrodes, Ca2+ removal abolished the carbachol responses in about 5 min (n=4). It was also found that tetraethylammonium (5 mM) strongly reduced both currents, by blocking muscarinic receptors, while Ba2+ (2.4 mM) inhibited only the outward K+ current.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00371115
