Multiple Analysis of Respiratory Activity in the Identical Oocytes by Applying Scanning Electrochemical Microscopy

Abstract

Scanning electrochemical microscopy (SECM) is a technique in which the tip of a microelectrode is used to scan and monitor the local distribution of electro-active species near the sample surface. In this study, we have studies on the SECM technique, to establish the accurate method for measurement of respiratory activity of single pig oocytes. The oxygen consumption rates of pig oocytes cultured in modified TCM199 medium were evaluated by the SECM system. After the measuring, distribution of active mitochondria and ATP content was investigated in the identical oocytes. The oocytes were classified in three types (Type-I, Type-II or Type-III) according to the pattern of active mitochondria distribution. There was no difference in the oxygen consumption rate (F x 10 14/mol s-1) between Type-II and Type-III (0.59 and 0.60, respectively). However, the ATP content (pmol/oocyte) was significantly higher in Type-III (2.38) compared with that of Type-II (1.53). Meanwhile, the oxygen consumption rate and ATP content of Type-I were very low (0.02 and 0.06, respectively). These results suggest that the oxygen consumption rate and ATP content of oocytes was significantly affected by category of mitochondrial distribution. In the present study, we succeeded in the multiple analysis of respiratory activity in the identical oocytes. This novel system may be a valuable tool for accurately assessing the mitochondrial functions.