A system is described for automatic feedback control of plasma potassium concentration in experimental animals. Plasma potassium was monitored continuously and the signal compared with the desired plasma potassium concentration. The resulting error signal controlled the infusion rates of a concentrated potassium chloride solution (50 or 200 mmol litre-1) and a solution of 50% glucose with insul...

1. The effect of extracellular potassium on the transport of sodium and potassium in rat thymocytes has been studied in vitro. 2. A significant increase in the rate constant for total and ouabain-sensitive sodium efflux was demonstrated at an extracellular potassium concentration of 1 mmol/l as compared with that at either 0 or 2 mmol/l. 3. At potassium concentrations below 3 mmol/l ouabain-sen...

1. The mechanism of potassium transport across human distal colon was investigated in twenty-two individuals without evidence of bowel disease, by using a dialysis method in conjunction with measurements of the transepithelial potential difference (p.d.). 2. Whether potassium was absorbed or secreted depended on its initial concentration in the lumen. The potassium net flux was approximately ze...

tion on the damaged area of the heart surface , we noted the following results'). Immediately after injury, the ST-elevation was, of course, recorded in the direct unipolar electrocardiogram taken from the injured heart surface . This elevation of the ST-segment was not eliminated even when potassium-free solution was poured on the injured region. As time passed, however, it did not make the ST...

Humans are intermittently exposed to large variations in potassium intake, which range from periods of fasting to ingestion of potassiumrich meals. These fluctuations would abruptly alter plasma potassium concentration if not for rapid mechanisms, primarily in skeletal muscle and the liver, that buffer the changes in plasma potassium concentration by means of transcellular potassium redistribut...

A readily reversible rise in pH of the medium occurs when unbuffered spinach chloroplasts are illuminated, especially when the initial pH during incubation in the dark is at or below 6.5 (1, 2). This rise in pH had been predicted from an examination of the chemiosmotic mechanisms for phosphorylation detailed by Mitchell (3). It was correlated, in at least a preliminary way, with the existence i...

We conducted this study to determine whether physiological changes in potassium concentration affect free radical formation by vascular cells. We assessed the effects of potassium on reactive oxygen species formed by cultured endothelial and monocyte/macrophage cells or freshly isolated human white blood cells by cytochrome c reduction or luminol chemiluminescence, respectively. Reducing potass...