[111] Biological applications of ion-specific glass electrodes

Publisher Summary This chapter examines the biological applications of ion-specific glass electrodes. In biological systems, the permeant ions most likely to be encountered by the electrodes are H + , Na + , and K + . Ion-specific glass electrodes have been employed extensively for measurement of the translocation of K + , Na + , and H + across the mitochondrial membrane. After the equilibration period, rapid ion movement is initiated by addition of minute amounts (10 -8 to 10 -1° M ) of certain antibiotics, for example, valinomycin, to the isolated mitochondria in an appropriate medium. The total ion concentration of the system as a whole remains constant; however, the concentration of an ionic species within the intramitochondrial phase lowers its activity in the extramitochondrial phase that is the phase sensed by the electrodes. Other interesting applications of the electrodes include the simultaneous monitoring in vivo of brain surface, cortex, and blood. For many biological applications, it is more convenient to calibrate electrode responses empirically by addition of standards to the test solution than compute ion concentrations from precise measurements of the electrode potentials. The chapter also discusses the special characteristics of electrodes.