The free magnesium concentration in the axoplasm of the giant axon of the squid, Loligo pealei, was estimated by exploting the known sensitivity of the sodium pump to intracellular Mg2+ levels. The Mg-citrate buffer which, when injected into the axon, resulted in no change in sodium efflux was in equilibrium with a Mg2+ level of about 3--4 mM. Optimal [Mg2+] for the sodium pump is somewhat high...

In salt-tolerant Chara longifolia, enhanced Na+ efflux plays an important role in maintaining low cytoplasmic Na+. When it is cultured in fresh water (FW), C. longifolia has a higher Na+ efflux than the obligate FW Chara corallina, although pH dependence and inhibitor profiles are similar for both species (1. Whittington and M.A. Bisson 119941 j Exp Bot 45: 657-665). When it is cultured in salt...

BACKGROUND One of the most important resistance mechanisms in bacteria is the increased expression of multidrug efflux pumps. To combat efflux-related resistance, the development of new efflux pump inhibitors is essential. MATERIALS AND METHODS Ten phosphorus ylides were compared based on their MDR-reverting activity in multidrug efflux pump system consisting of the subunits acridine-resistan...

The efflux of Ca2+ from both cardiac and skeletal-muscle mitochondria loaded with 25 nmol of Caz+/mg of protein into a salt-free medium is shown in the form of an Arrhenius plot in Fig. 1. Basal efflux of Caz+ from cardiac and muscle mitochondria increases as the temperature is raised from 17 to 41OC; the respective activation energies are 53 and 87kJ/mol. Between 17 and 34OC Na+-stimulated eff...

Well-established techniques are available to predict in vivo hepatic uptake and metabolism from in vitro data, but predictive models for biliary clearance remain elusive. Several studies have verified the expression and activity of ATP-binding cassette (ABC) efflux transporters central to biliary clearance in freshly isolated rat hepatocytes, raising the possibility of predicting biliary cleara...

In addition to being a general anaesthetic, ketamine is a recognized drug of abuse. Many, if not all, drugs of abuse have been shown to increase dopamine efflux in the nucleus accumbens (NAc). As ketamine is optically active, we examined if its actions on dopamine efflux in the NAc were stereoselective. Slices of rat NAc were superfused with artificial CSF at 32 degrees C. Dopamine efflux was e...

The effects of insulin and ouabain on 22Na efflux and net Na loss were examined in frog sartorius muscles. After removal of ouabain, 22Na efflux which had been inhibited by ouabain remained at the inhibited level for more than 2 hr. In ouabain-free solution, insulin stimulated the Na efflux from ouabain-preincubated muscles. The stimulating effect of insulin on 22Na efflux was completely blocke...

Well-established techniques are available to predict in vivo hepatic uptake and metabolism from in vitro data, but predictive models for biliary clearance remain elusive. Several studies have verified the expression and activity of ATP-binding cassette (ABC) efflux transporters central to biliary clearance in freshly isolated rat hepatocytes, raising the possibility of predicting biliary cleara...

The transepithelial efflux of Na and several nonelectrolytes (mannitol, sucrose, and polyethylene glycol 900) were measured in the isolated frog skin under short-circuited conditions in chambers that had been specially designed to avoid edge damage. Ouabain (10(-3) and 10(-4) M) caused a dramatic increase in the efflux of Na, whereas the efflux of nonelectrolytes showed only a slight alteration...

BACKGROUND AND AIMS Aluminium (Al) stimulates the efflux of citrate from apices of rice bean (Vigna umbellata) roots. This response is delayed at least 3 h when roots are exposed to 50 microm Al, indicating that some inducible processes leading to citrate efflux are involved. The physiological bases responsible for the delayed response were examined here. METHODS The effects of several antago...