A novel resin-filled ion-sensitive micro-electrode suitable for intracellular measurements in isolated cardiac myocytes.

A method for the manufacture of ion-sensitive micro-electrodes, which can be readily used with small single cells, is described in detail. A glass pipette with a tip size of 1 micron, essentially similar to those used as suction electrodes in whole-cell recording, when silanized and with its tip filled with a suitable ion-sensitive resin, produces an ion-sensitive electrode with fast electrical and chemical response times. These electrodes can be applied to the cell membrane of isolated myocytes and penetration achieved without cell damage, by the application of suction. For the estimation of intracellular ionic activities they can be used in conjunction with a separate conventional KCl-filled micro-electrode or a suction voltage electrode. The technique is illustrated by the measurement of intracellular Na+, Ca2+ and pH. It is possible that these electrodes can also be used to measure local changes in ionic activity in restricted areas.