AJP - Cell Physiology, Vol 271, Issue 6 C1920-C1926, Copyright © 1996 by American Physiological Society
Study of nonspecific cation channel coupled to P2z purinergic receptors using an acid load technique
M. Lachish, E. Alzola, N. Chaib, M. Metioui, K. Grosfils, E. Kabre, A. Moran, A. Marino and J. P. Dehaye
Department of Physiology, Corob Center for Medical Research, Faculty for Health Science, Ben-Gurion University, Beer-Sheva, Israel.
The intracellular pH (pHi) of rat submandibular cells was measured by
2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). The cells
recovered from ammonium (30 mM) prepulse to their resting pHi within 10
min. Ethylisopropylamiloride (EIPA), an inhibitor of the Na+/H+ exchanger,
slows the rate of pHi recovery. ATP (1 mM), in the presence of EIPA,
increases the rate of recovery 3.7-fold in the absence or presence of
ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. The
recovery was blocked by the addition of 5 mM Mg2+ or 10 microM Coomassie
blue. The response was elicited by 2'- and
3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate but not by ADP, UTP,
adenyl (beta-gamma-methylene)-diphosphonate, 2-methylthioadenosine
5'-triphosphate, or muscarinic or beta-adrenergic agonists. The purinergic
response was also observed when the cells were acidified by sodium
propionate and could not be mimicked by the depolarization of the plasma
membrane. Aluminum fluoride did not reproduce the response to ATP,
suggesting that the observed response does not involve a
high-molecular-weight GTP-binding protein. It is concluded that the
activation of P2z receptors, probably by the opening of nonspecific cation
channels, increases the permeability to protons in rat submandibular
glands.
