AJP - Cell Physiology, Vol 237, Issue 3 177-C184, Copyright © 1979 by American Physiological Society
Mechanical properties and functions of the myoepithelium in the eccrine sweat gland
K. Sato, A. Nishiyama and M. Kobayashi
Contractile properties of an isolated segment of the secretory coil of the
monkey palm eccrine sweat gland were studied in vitro with a transducer.
Contraction of up to 10 mgf was induced with acetylcholine but not with
alpha or beta adrenergic agonists, caffeine, prostaglandin E1, or by a
calcium ionophore A23187. Other features included K+ contracture, staircase
effect, poor extensibility, length-tension relationship with a peak tensile
response at 115--120% of the resting length, and requirement of Ca2+. The
function of myoepithelium is unlikely to expulse the preformed sweat
because the amount of preformed sweat is small, K+-contracture failed to
expulse sweat, and because myoepithelial contraction was not induced by
such stimulants of sweat secretion as A23187, phenylephrine, isoproterenol,
and prostaglandin E1. The maximal transverse tension of 20 mgf during
acetylcholine stimulation under resting tension was calculated to support
the luminal hydrostatic pressure of approximately 500 mmHg. Thus the
function of the myoepithelium may be to render structural support for the
secretory epithelium.
