Potassium regulation mechanism

The mechanism by which potassium regulates aldosterone secretion is unclear however, this ion appears to have a direct effect on the adrenal cortex. An increase in the level of potassium in the blood stimulates the release of aldosterone. The effect of aldosterone on the kidney then decreases the level of potassium back to normal. 

Similarly, if renal system function is insufficient or nonexistent (failure), reabsorption and excretion of electrolytes may occur without response to the feedback mechanism or consideration of current levels of electrolytes. For example, in renal failure, potassium may be not be excreted and may even be reabsorbed, although the potassium level is already high because there is a failure of the usual feedback mechanism. Table 1-3 is a summary of regulation mechanisms for representative electrolytes. 

Additional cellular events linked to the activity of blood pressure regulating substances involve membrane sodium transport mechanisms Na+/K.+ ATPase Na+fLi countertransport Na+ -H exchange Na+-Ca2+ exchange Na+-K+ 2C1 transport passive Na+ transport potassium channels cell volume and intracellular pH changes and calcium channels. 

Describe the process by which potassium ions are secreted and the mechanism that regulates this process... 

A normal diet contains a sufficient amount of both sodium and potassium. The body has specific mechanisms for regulating the Na ion concentration, which is important in the control of blood pressure (Chapter 22). However, there is less potassium in the normal diet and it may not always be sufficient (e.g. if the sweating rate is high). Fruit and fruit juices are good natural sources of this electrolyte. 

Given chloride s role in ruminal absorption and CSF secretion, perhaps its participation in the aldosterone mechanism of regulating the sodium/potassium axis" should cunie us no surprise. 

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