Potassium transport in Langendorff-perfused mouse hearts assessed by 87Rb NMR spectroscopy

✍ Scribed by Olga Jilkina; Bo Xiang; Bozena Kuzio; John Rendell; Valery V. Kupriyanov

• Book ID: 102532700
• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 211 KB
• Volume: 53
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.20450

✦ Synopsis

Abstract

We studied the fluxes of a potassium congener (Rb^+^) in mouse hearts by ^87^Rb MRS at 8.4T. The hearts were loaded with Rb^+^ by perfusion with Krebs‐Henseleit buffer, in which 50% of K^+^ was substituted with Rb^+^. We initiated Rb^+^ efflux by changing the perfusion medium to Rb^+^‐free buffer. Spectra were acquired every 1.85 min, and the kinetics of Rb^+^ transport were analyzed by means of monoexponential fits. The rate constants of Rb^+^ uptake and efflux were 0.0680 ± 0.0028 and 0.0510 ± 0.0051 min^–1^, respectively (∼30% faster than in the rat heart). The ATP‐sensitive potassium channel opener, P‐1075 (5 μM), and mitochondrial uncoupler, 2,4‐dintrophenol (50 μM), activated Rb^+^ efflux from mouse hearts by ∼35%. The mechanisms responsible for the differences in Rb^+^ uptake and efflux under baseline conditions and stimulation, in comparison with rat hearts, are discussed. These data provide a background for studies of cardiac potassium transport in transgenic mouse strains. Magn Reson Med 53:1172–1176, 2005. © 2005 Wiley‐Liss, Inc.