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Relationship between quin2-determined cytosolic [Ca2+] and sweat secretion
1Marshall Dermatology Research Laboratories, Department of Dermatology, University of Iowa School of Medicine, Iowa City 52242.
The American Journal of Physiology
|February 1, 1988
Summary
Methacholine (MCh) increases intracellular calcium in sweat cells, but A23187 does not stimulate secretion, suggesting complex calcium signaling in eccrine sweating.
Area of Science:
- Physiology
- Cell Biology
- Biochemistry
Background:
- Extracellular calcium is crucial for methacholine (MCh) and A23187-induced sweat secretion.
- The specific role of intracellular calcium concentration ([Ca2+]i) in eccrine sweat gland function remains unclear.
Purpose of the Study:
- To investigate the role of intracellular calcium concentration ([Ca2+]i) in eccrine sweat secretion.
- To determine how MCh and A23187 affect [Ca2+]i and sweat secretion in isolated monkey sweat glands.
Main Methods:
- Isolation of eccrine secretory cells from monkey sweat glands using collagenase digestion and Percoll gradient centrifugation.
- Quantification of intracellular calcium concentration ([Ca2+]i) using the quin2 method.
- Measurement of sweat secretion and CO2 production in vitro.
Main Results:
- MCh dose-dependently increased [Ca2+]i in a calcium-dependent manner (resting levels 80-320 nM).
- A23187 (10(-7) M) increased [Ca2+]i to approximately 900 nM.
- Theophylline (TH), isoproterenol (ISO), and forskolin (FK) did not affect resting [Ca2+]i but attenuated MCh and A23187 effects.
- A23187 failed to stimulate sweat secretion or CO2 production in intact glands or dispersed cells, respectively.
Conclusions:
- A dissociation exists between increased [Ca2+]i and sweat secretion stimulated by A23187.
- MCh may involve additional signaling pathways beyond just increased [Ca2+]i.
- A23187-induced calcium influx might be less efficient in undissociated sweat glands compared to isolated cells.