*Natural Medicinal Plants*

#### *Natural Products Altering GABAergic Transmission DOI: http://dx.doi.org/10.5772/intechopen.99500*

saturation, kinetic, and inhibition. A saturation curve can be made by considering amount of receptor as constant and concentration of radioligand as variable. From this type of experiment the receptor density and the affinity of the receptor for the radioligand can be estimated. If the amount of receptor and radioligand is constant and the time is the variable, then kinetic data which are obtained from forward and reverse rate constants can be assessed. If the amount of a competing nonradioactive drug included in the incubation is the only variable, then the affinity (Ki) of that drug for the receptor identified by the radioligand can be estimated [61].

In Xenopus oocytes assay, xenopus oocytes are the immature egg cells of the South African clawed frog *Xenopus laevis*, these have striking appearance with two colors, the light colored vegetal pole and the dark animal pole, where the nucleus is found. TEVC recording (This method is a type of patch-clamp electrophysiology method to inject current into a cell with one electrode and recording the change in voltage with the other electrode) is used to measure membrane potential of the oocyte is clamped at a constant value. Two electrodes spear the oocytes in which one intracellular microelectrode measures the membrane potential (voltage electrode) and the second one (intracellular microelectrode) controls the current. This is also called current electrode and uses as a feedback circuit to pass sufficient current to the oocyte for maintaining the voltage clamp. The current which is flowing through the current electrode can provide a measurement of the of chloride specific ion channels [62].
