Bicarbonate attenuates intracellular acidosis

• Published in: Acta anaesthesiologica Scandinavica Vol. 46; no. 5; pp. 579 - 584
• Main Authors: Nielsen, H. B., Hein, L., Svendsen, L. B., Secher, N. H., Quistorff, B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Munksgaard International Publishers 01.05.2002; Blackwell
• Subjects: Acidosis - drug therapy; Acidosis - physiopathology; Adult; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; bicarbonate; Bicarbonates - therapeutic use; Biological and medical sciences; Blood Gas Analysis; buffer; Buffers; Carbon Dioxide - blood; Emergency and intensive care: metabolism and nutrition disorders. Enteral and parenteral nutrition; Exercise - physiology; Hand Strength - physiology; Humans; Intensive care medicine; intracellular acidosis; Magnetic Resonance Spectroscopy; Male; Medical sciences; Muscle Contraction - physiology; Human; Intravenous administration; Acid base balance disorder; Striated muscle; Hydrogencarbonates; Metabolic disorder; Chemotherapy; Treatment; Perfusion; pH; Intracellular; Lactic acid; Acidosis; Metabolic acidosis
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1034/j.1399-6576.2002.460516.x

Background: This study was prompted by concern that administration of bicarbonate for correction of lactate acidosis aggravates a low intracellular pH (pHi). In healthy subjects we evaluated skeletal muscle pHi using 31P‐magnetic resonance spectroscopy during 5‐minute rhythmic handgrip to provoke intracellular acidosis. Methods: Subjects were randomized to treatment with bicarbonate or saline infused intravenously in a cross‐over study design with 1 h between trials. Results: In response to rhythmic handgrip, muscle venous O2 hemoglobin saturation decreased from 51 ± 4% to 36 ± 2% and lactate increased from 1.0 ± 0.1 to 4.9 ± 0.5 mmol/l with a reduction in pH from 7.43 ± 0.01–7.23 ± 0.01 (P<0.05). pHi decreased from 7.06 ± 0.02–6.36 ± 0.08 (P<0.05). Infusion of bicarbonate increased the arterial blood concentration from 26 ± 1 to 39 ± 1 mmol/l (P<0.05). The arterial CO2 partial pressure decreased from 5.6 ± 0.2 to 5.2 ± 0.3 kPa during rhythmic handgrip, whereas it increased to 5.9 ± 0.2 kPa (P<0.05) during infusion of bicarbonate. Bicarbonate treatment also increased pH of arterial and venous blood (7.55 ± 0.01 vs. 7.44 ± 0.02 and 7.31 ± 0.01 vs. 7.23 ± 0.02, respectively; P<0.05). In the last min of rhythmic handgrip the decrease in pHi was attenuated by the administration of bicarbonate (6.60 ± 0.11 vs. 6.40 ± 0.12; P<0.05). Conclusion: During exercise‐induced metabolic acidosis, intravenous administration of bicarbonate increased the buffering capacity of blood and attenuated the decrease in intracellular muscle pH, although there was a small increase in the arterial carbon dioxide pressure.