Effect of storage conditions on lactate dehydrogenase released from perfused hearts

Background Release of lactate dehydrogenase (LDH) is a widely used marker of tissue damage. A review of the literature indicates that after collection of coronary effluents from hearts, a variety of storage conditions have been utilized prior to measurement of LDH activity. The purpose of this study was to determine whether storage conditions reported in the literature affect LDH activity. Methods Isolated rat hearts perfused with Krebs–Henseleit buffer (KHB) were subjected to 30 min of global ischemia followed by normoxic reperfusion to generate tissue damage and elevate LDH release. Coronary effluents were collected and stored at 4 °C, 23 °C, − 20 °C, and − 80 °C prior to measurement of LDH activity. Results After 24 h no decline in LDH occurred at 4 °C storage (P > 0.05), but a 42% decline occurred at 23 °C (P < 0.05). After 48 h, activity declined (P < 0.05) 11% at 4 °C and 98% at 23 °C. Frozen storage resulted in a 40% loss at − 80 °C and a 79% loss at − 20 °C (P < 0.05). Conclusions Short-term storage in Krebs–Henseleit buffer for 24 h at 4 °C does not affect LDH activity and frozen storage should be avoided.