23Na NMR shift reagents enhance cardiac staircase effect in isolated perfused rat hearts

✍ Scribed by Tamás Simor; Tamás Lóránd; Áron Szöllösy; Balázs Gaszner; Stanley B. Digerness; Gabriel A. Elgavish

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 114 KB
• Volume: 12
• Category: Article
• ISSN: 0952-3480
• DOI: 10.1002/(sici)1099-1492(199908)12:5<267::aid-nbm562>3.0.co;2-1

✦ Synopsis

The effects of the currently used 23 Na NMR shift reagents, dysprosium bis-triphosphate [Dy(PPP) 2 ], dysprosium triethylenetriamine hexaacetate [Dy(TTHA)] and thulium 1,4,7,10-tetraazacyclododecane-N,N',N@,N-tetra(methylenephosphonate) [Tm(DOTP)] were studied in the rat heart cardiac staircase model. Rat hearts were perfused with low or normal extracellular free calcium ([Ca o ] f ). At low [Ca o ] f (0.34 AE 0.05 mM), hearts were perfused with Dy(PPP) 2 (group I), Dy(TTHA) (group II) or no shift reagent (group III), while at normal [Ca o ] f (1.25 AE 0.15 mM), hearts were perfused with Tm(DOTP) (group IV), Dy(TTHA) (group V) or no shift reagent (group VI). Left ventricular developed pressure (LVDP) values in group I were significantly higher than in groups II and III (p 0.01), while no significant differences were found between groups II and III. LVDP values in group IV were significantly higher than in groups V and VI (p 0.05), while the LVDP values in groups V and VI were almost identical. Also, a positive correlation between pacing rate and intracellular sodium ([Na i ]) was evident. The [Na i ] values at high [Ca o ] f were significantly lower than at low [Ca o ] f at each pacing level (p `0.01), indicating a negative correlation between [Na i ] and [Ca o ] f . No statistical differences were found in [Na i ] between groups I vs II and IV vs V, showing that determination of [Na i ] is not affected by any of these shift reagents. Thus the different LVDP responses in groups I vs II and IV vs V were not mirrored in [Na i ] changes. We hypothesize that a direct, sarcolemmal Ca-Dy(PPP) 2 -, or Ca-Tm(DOTP)-induced positive inotropic effect could be responsible for these Na i -independent LVDP increases in groups I and IV.