Comparação sérica e sangüínea do cálcio ionizado, sódio, potássio e cloreto em felinos pelo método eletrodo íon seletivo / Serum and blood comparison of ionized calcium, sodium, potassium and chloride in cats, by ion-selective electrode method

Values of sodium, ionized calcium, potassium and chloride obtained by ion-selective electrode method, from serum and blood samples of healthy cats, were compared. Serum ionized calcium value was lower (5.2mg/dl) than blood ionized calcium (5.4mg/dl), and serum potassium (4.47mmol/l) and serum chloride (117.2mmol/l) values were higher than blood potassium (3.94mmol/l) and blood chloride (115mmol/l).

Comparação sérica e sangüínea do cálcio ionizado, sódio, potássio e cloreto em felinos pelo método eletrodo íon seletivo / Serum and blood comparison of ionized calcium, sodium, potassium and chloride in cats, by ion-selective electrode method

Values of sodium, ionized calcium, potassium and chloride obtained by ion-selective electrode method, from serum and blood samples of healthy cats, were compared. Serum ionized calcium value was lower (5.2mg/dl) than blood ionized calcium (5.4mg/dl), and serum potassium (4.47mmol/l) and serum chloride (117.2mmol/l) values were higher than blood potassium (3.94mmol/l) and blood chloride (115mmol/l).

pH-dependent modulation of intracellular free magnesium ions with ionselective electrodes in papillary muscle of guinea pig

A change in pH can alter the intracellular concentration of electrolytes such as intracellular Ca2+ and Na+ ([Na+]i) that are important for the cardiac function. For the determination of the role of pH in the cardiac magnesium homeostasis, the intracellular Mg2+ concentration ([Mg2+]i), membrane potential and contraction in the papillary muscle of guinea pigs using ion-selective electrodes changing extracellular pH ([pH]o) or intracellular pH ([pH]i) were measured in this study. A high CO2-induced low [pH]o causes a significant increase in the [Mg2+]i and [Na+]i, which was accompanied by a decrease in the membrane potential and twitch force. The high [pH]o had the opposite effect. These effects were reversible in both the beating and quiescent muscles. The low [pH]o-induced increase in [Mg2+]i occurred in the absence of [Mg2+]o. The [Mg2+]i was increased by the low [pH]i induced by propionate. The [Mg2+]i was increased by the low [pH]i induced by NH4Cl-prepulse and decreased by the recovery of [pH]i induced by the removal of NH4Cl. These results suggest that the pH can modulate [Mg2+]i with a reverse relationship in heart, probably by affecting the intracellular Mg2+ homeostasis, but not by Mg2+ transport across the sarcolemma.