Abstract
OBJECTIVE: This study aimed to investigate whether St. Thomas' Hospital No. 2 solution (STH2) is equally effective in both young and aged aquaporin-7-knockout (AQP7-KO) mice and the mechanisms by which the intra-myocardial adenosine triphosphate (ATP) content is altered during ischemia without aquaporin-7. METHODS: In study 1, isolated hearts of male wild-type (WT) and AQP7-KO mice (< 12 weeks old) were Langendorff perfused with 5-min STH2 prior to a 20-min global ischemia (GI) or 25-min GI without STH2. Similarly, in Study 2, hearts from WT and AQP7-KO mice (≥ 24 weeks old) were subjected to 2-min STH2 infusion prior to GI. In study 3, intra-myocardial ATP content was compared before (sham) and after (control or STH2) ischemia in mature WT and AQP7-KO mice. RESULTS: In study 1, troponin T levels (ng/g wet weight) of WT and AQP7-KO hearts were significantly lower in the STH2 groups (75.6 ± 45.9 and 80.2 ± 52.2, respectively) than in the GI groups (934.0 ± 341.1 and 1089.3 ± 182.5, respectively). In Study 2, troponin T levels in aged WT and AQP7-KO mice were 566.5 ± 550.0 and 547.8 ± 594.3, respectively (p = 0.9561). In Study 3, ATP levels (μmol/g protein) in the sham, control, and STH2 AQP7-KO mice groups were 4.45, 2.57, and 3.37, respectively(p = 0.0005). CONCLUSIONS: The present study revealed the cardio-protective efficacy of STH2 in an experimental model of isolated AQP7-KO young and aged murine hearts. Further, STH2 preserved intra-myocardial ATP during ischemia with Krebs-Henseleit buffer perfusion in the Langendorff setting.