Renal potassium regulation in a pig model of therapeutic hypothermia

• Published in: Physiology (Bethesda, Md.) Md.), 2024-05, Vol.39 (S1)
• Main Authors: Uyehara, Catherine, Wong, Lauren, Murata, Lee-Ann, Bailey, Emily, Hernandez, Claudia, Maxwell, Reynaldo, Aponte Gonzalez, Ivanyelise
• Format: Article
• Language: English
• ISSN: 1548-9213; 1548-9221
• DOI: 10.1152/physiol.2024.39.S1.1740

Abstract only Therapeutic hypothermia is increasingly utilized clinically to reduce tissue metabolism and protect against neurological damage in cases of cardiac arrest, traumatic brain injury or perinatal hypoxic ischemia. With even mild exposure to hypothermia, hypokalemia develops purportedly due to transcellular potassium shifts resulting in decreased circulating potassium levels. Renal dysfunction with body temperature cooling has also been postulated to potentially contribute to development of sustained hypokalemia. In this study, we used a pig model of controlled acute hypothermia without confounding hypotension and hypoxemia, to test the hypothesis that renal handling of potassium remains intact in hypothermia and is not the cause of decreased circulating plasma potassium seen with body cooling. Anesthetized, mechanically ventilated Duroc cross young pigs (n=25, body weight = 10.0 ± 0.4 kg, male or female) were catheterized for hemodynamic monitoring, regional blood flow assessment via colored microspheres, and urine collection. After baseline values were obtained, pigs were divided into a control normothermia group (n=12) with body temperature maintained at 38.4 ± 0.1 o C or a hypothermia group (n=13) with core body temperature cooled to 34.5 ± 0.1 o C and hypothermia sustained for 2 hours. Hypothermia reduced tissue metabolism as indicated by a decrease in oxygen consumption (VO 2 = 5.2 ± 0.2 ml/kg in normothermia vs 3.7 ± 0.3 ml/kg in hypothermia. Mean arterial pressure (68± 3 mm Hg) and cardiac output (199 ± 21 ml/min/kg) were not different between groups. Even with the short duration of cold exposure, plasma potassium was lower (p