Dynamics of interstitial calcium in rat myocardial ischemia reperfusion injury in vivo

Intracellular calcium overload is a key factor for myocardial ischemia reperfusion injury (IR). However, there was no report for interstitial calcium concentration dynamics. We investigated the interstitial calcium dynamics in rat myocardial IR model in vivo. A microdialysis system was involved, and the time delay of the system and recovery time was introduced and tested with a fluids switching method. Twelve SD rats were divided into IR or control group. Myocardial IR was induced by ligating (20 min) then releasing (60 min) the suture underlying left anterior descending branch. Mycrodialyisis probe was implanted into the left ventricular myocardium perfusion area for occlusion. Dialysate samples were collected every 10 min. Dialysate calcium concentration was detected with an atomic absorption spectrophotometer. Recovery time for the microdialysis system was 20 min, and recovery rate was 16%. Dialysate calcium concentration showed no changes during ischemia, descended immediately after reperfusion, reached the lowest level (67% of baseline value) 20 min after reperfusion, then escalated slowly. Recovery time was an important parameter for mycrodialysis technique, and it should not be neglected and needed to be tested. Our data suggest that interstitial calcium concentration in rats with myocardial IR in vivo kept steady in ischemia, descended rapidly at the initial reperfusion, then rebounded slowly. In conclusion, we introduced the concept of recovery time for microdialysis and provided a simple testing method.