Potassium turnover was studied in rainbow trout, Salmo gairdneri Richardson, adapted to fresh water or 22 %o sea water using K and Rb. Potassium space of the whole body increased with time and was about 5 mmol kg" after 20h, while Rb space under the same conditions was only about 0-5 mmol kg", indicating slow penetration of body K by Rb + , especially in muscle and red blood cells. Potassium in...

We tested the hypothesis that potassium ion (K+) is involved in the local control of the coronary circulation. The left coronary artery was perfused at constant flow in closed-chest, anesthetized dogs. Step increases in heart rate caused transient (six dogs) or sustained (three dogs) increases in coronary sinus plasma [K+] averaging 0.53 mEq/liter. When the effects of vascular transit delay wer...

Rat kidneys perfused outside of the body with an artificial medium are able to increase their fractional excretion of potassium in response to a rising concentration of potassium in the medium but never show net secretion of potassium. By contrast, isolated perfused kidneys from chronically potassium-loaded rats regularly secrete potassium in excess of the amount filtered. Ouabain completely bl...

nonexchangeable soil-k release rate can significantly affect k dynamics and it's bioavailability during plant growth. in this study, twelve soil samples taken from different wheat cropping regions of iran were incubated with nabph4 to (i) investigate the kinetics of nonexchangeable k release and (ii) to compare the ability of various kinetic equations (zero-, first- and second-order, parab...

Two methods of in vivo continuous microperfusion were used to evaluate separately luminal sodium concentration and fluid flow rate as factors regulating potassium secretion by the renal distal tubule of the rat. Emphasis was placed on evaluating changes in sodium concentration (43-97 mM) and flow rate (4-27 nl/min) within the physiological range. Absolute rates of Na, K, Cl, and H2O transport w...

In a pot culture experiment, the root length density, potassium concentration in crop, and total K uptake by wheat (Triticum aestivum var. HD 2285) at different growth stages (CRIS-Crown Root Initiation Stage, MTS-Maximum Tillering Stage, FLS-Flag Leaf Stage and DFS-Dough Formation Stage) were determined. Wheat crop was grown in 72 pots containing 4.5 kg of three types of soils, namely Alfisol,...

as the basis for epileptogenic discharges, the action of DPH on K transport within synaptic terminals isolated from "normal" rat brain cortex was examined directly. A rapid filtration technique was used to assess in vitro potassium transport within synaptosomes. In vivo DPH did not significantly change endogenous K content within synaptosomes. With sodium (50 mM) and potassium (10 mM) concentra...

A randomized complete block design was used to characterize the relationship between production of total phenolics, flavonoids, ascorbic acid, carbohydrate content, leaf gas exchange, phenylalanine ammonia-lyase (PAL), soluble protein, invertase and antioxidant enzyme activities (ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) in Labisia pumila Benth var. alata under f...

The K(ir)4.1 channel is crucial for the maintenance of the resting membrane potential of glial cells, and it is believed to play a main role in the homeostasis of extracellular potassium. To understand its importance in these two phenomena, we have measured in vivo the variations of extracellular potassium concentration ([K(+)](o)) (with potassium-sensitive microelectrodes) and membrane potenti...