Figure 633

Changes in urine acid-base composition during development, maintenance, and correction of vomiting-induced metabolic alkalosis. During acid removal from the stomach as well as early in the phase after vomiting (maintenance), an alkaline urine is excreted as acid excretion is suppressed, and bicarbonate excretion (in the company of sodium and, especially potassium; see Fig. 6-32) is increased, with the net acid excretion being negative (net alkali excretion). This acid-base profile moderates the steady-state level of the resulting alkalosis. In the steady state (late maintenance phase), as all filtered bicarbonate is reclaimed the pH of urine becomes acidic, and the net acid excretion returns to baseline. Provision of sodium chloride (NaCl) and potassium chloride (KCl) in the correction phase alkalinizes the urine and suppresses the net acid excretion, as bicarbonaturia in the company of exogenous cations (sodium and potassium) supervenes [22,23]. HCO3—bicarbonate ion.


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