[Interaction of alkaline earth and transition metals with Na+/Ca2+-plasma membrane exchanger in secretory cells of the gastric gland].
Investigation of Na(+)-dependent Ca2+ uptake into the secretory cells of isolated gastric glands from guinea pig with the use of calcium isotope (45Ca2+) has been performed. The presence of Na+/Ca(2+)-exchanger in the cells membrane was established. Ca2+ uptake into the cells through Na+/Ca(2+)-exchanger was competitively inhibited by the number of alkaline earthy and transient metals" cations. Potency of inhibition increases in such an order (Ki, mM): Ba2+ (117.7) < Sr2+ (53.4) < < Mn2+ (15.2) < < Co2+ (12.8) < Cd2+ (8.6). By one-factor dispersion analysis it was shown that potency of inhibition depends on ionic radii and hydration enthalpy of metals" cations (hx2 = 93.93-94.15%) and also on stability constants of their complexes with oxygen-containing bioligands (acetic, aspartic and glutamic acid) (hx2 = 82.32-82.47%). Dependence of inhibitory constants from ionic radii is most adequately described by the parabolic equation, such dependence from hydration enthalpy and stability constants with oxygen-containing bioligands--by exponential or multiplicative equations. The conclusion has been made that velocity of Ca2+ transport through Na+/Ca(2+)-exchanger and potency of its inhibition by metals" cations is determined by the interaction between energy of their interaction with cation-binding sites of transport system and energy of hydration. Energetics of such interactions mainly depends on the steric conformity between the metal cation and cation-binding sites of the exchanger.
Dubyts'kyĭ
L O
LO
Ivan Franko National University of Lviv, Ukraine.
Vovkanykh
L S
LS
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002412:Cations; D005753:Gastric Mucosa / Q000378:metabolism*; D006168:Guinea Pigs; D008670:Metals / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013270:Stomach / Q000166:cytology
D002412:Cations; D008670:Metals; D012964:Sodium; D002118:Calcium