Na+/H+ exchange in human lymphocytes and platelets in chronic and subacute metabolic acidosis

• Published in: The Journal of clinical investigation Vol. 92; no. 2; pp. 858 - 865
• Main Authors: REUSCH, H. P, REUSCH, R, ROSSKOPF, D, SIFFERT, W, MANN, J. F. E, LUFT, F. C
• Format: Journal Article
• Language: English
• Published: Ann Arbor, MI American Society for Clinical Investigation 01.08.1993
• Subjects: Acidosis - blood; Acidosis, Renal Tubular - blood; Acute Disease; Biological and medical sciences; Blood Platelets - metabolism; Carbon Dioxide - blood; Carrier Proteins - metabolism; Chronic Disease; Electrolytes - blood; Fluoresceins; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Kinetics; Lymphocytes - metabolism; Male; Medical sciences; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Renal failure; Sodium - blood; Sodium-Hydrogen Exchangers; Human; Urinary system disease; Nephropathy; Pathophysiology; Sodium; Hydrogen; Renal failure; Metabolic diseases; Renal disease; Acid base balance disorder; Ion exchange; Metabolic acidosis
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/JCI116660

The effect of acid-base disturbances on sodium/proton (Na+/H+) exchange has been examined in animal models; however, few data are available from human studies. To test the effect of metabolic acidosis on Na+/H+ exchange in man, as well as to examine the relationship between Na+/H+ exchange and cytosolic calcium ([Ca2+]i), we measured both variables in patients with decreased renal function with mild metabolic acidosis (pH 7.34 +/- 0.06), in normal control subjects (pH 7.41 +/- 0.02), and in subjects before (pH 7.40 +/- 0.01), and after (pH 7.26 +/- 0.04) ammonium chloride (NH4Cl) 15 g for 5 d. Lymphocytes and platelets were loaded with the cytosolic pH (pHi) indicator 2'-7'-bis(carboxyethyl)-5,6-carboxyfluorescein and acidified to pH approximately 6.6 with propionic acid. To quantitate Na+/H+ exchange, dpHi/dt was determined at 1 min. [Ca2+]i was measured with fura-2. Na+/H+ exchange was significantly increased only in lymphocytes of patients with renal insufficiency. Neither intracellular pH (pHi) nor [Ca2+]i was different from controls. NH4Cl resulted in a significant increase in Na+/H+ exchange in lymphocytes, but not in platelets of normal subjects. Values of pHi and [Ca2+]i in either cell type remained unaffected. Since metabolic acidosis influenced Na+/H+ only in lymphocytes, but not in platelets, it is possible that protein synthesis may be involved in increasing Na+/H+ exchange.