ISSN:
1432-2013
Keywords:
Salivary secretion
;
Acetylcholine
;
Epinephrine
;
Intracellular Ca2+
;
Amylase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Ca-selective microelectrodes were used to examine calcium transport during acetylcholine (ACh) and Epinephrine (Ep) stimulation of amylase secretion in the parotid gland. The cytosolic concentration of free ionized Ca2+ ([Ca]i) determined in unstimulated cells was 0.44 ±0.04 μM. By measuring the induced changes in intracellular electrode potentials (ECa, EM) we were able to demonstrate that ACh at 10−9, 10−8, 10−7, 10−6, and 10−5 M increased [Ca]i by 0.20±0.02, 0.61±0.04, 0.53±0.02, 0.30±0.05, and 0.14±0.03 μM. Similarly, Ep increased [Ca]i by 0.14±0.01, 0.42±0.06, 0.31±0.04, 0.15±0.03, and 0.05±0.04, respectively. Removal of extracellular Ca2+ significantly (P〈0.001) altered the changes in ECa in response to ACh and Ep stimulation, thereby demonstrating that the induced increases in [Ca]i must be due to a transmembrane movement of Ca2+. Enzyme secretion was found to vary with the concentration of the stimulus used. Maximal secretion occurred during stimulation using 10−7 M and 10−8 M Ep with a suppression of release at supramaximal concentrations. The dose-response curve for ACh differed in that there were two concentrations of stimulus (2×10−9 and 1×10−6 M ACh) in which the greatest rate of secretion occurred. Concentrations of stimulus which increase [Ca]i between 0.86±0.06 μM and 0.74±0.05 appeared to produce optimal amylase secretion, indicating that salivary secretion in the mouse parotid is regulated within a narrow concentration range of cytosolic Ca2+.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00657159
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