AJP - Cell Physiology, Vol 262, Issue 3 C760-C765, Copyright © 1992 by American Physiological Society
Triggering by ATP of product release by mucous granules of the land slug Ariolimax columbianus
I. Deyrup-Olsen, H. Louie, A. W. Martin and D. L. Luchtel
Department of Zoology, University of Washington, Seattle, Washington 98195.
The body wall of the pulmonate land slug Ariolimax columbianus secretes
mucus packaged in granules bounded by two closely adjacent membranes. Newly
secreted granules rupture in the presence of ATP (approximately 1 microM).
This response is apparently mediated by an ATP receptor and is lost by
granules held in osmotically balanced saline solutions with relatively low
[K+] or [Cl-], but is retained for long periods in solutions with high [K+]
and [Cl-]. Rupture by ATP is blocked by indomethacin, furosemide,
nigericin, or verapamil, implicating in the ATP-rupturing process a
cyclooxygenase product of arachidonic acid as well as activation of
K(+)-Cl- transport and efflux of Ca2+ through activated channels according
to a proposed electrical potential (proton) gradient. Mechanical stress,
exposure to cold (e.g., 1 h at 0 degree C), and pertussis toxin also cause
rupture that is blocked by the pharmacological agents that block ATP
action. The results suggest that a single basic mechanism causes rupture of
the granules, releasing mucins that form the mucous layer protecting the
body wall.
