Functional receptors expressed in Xenopus oocytes from the injection of hippocampal membranes. Responses of oocytes injected with hippocampal membranes (upper 2 traces) to the applications of A) 100 μM glutamate plus 20 μM cyclothiazide (CTZ), B) 1 mM GABA, C) 10 μM NECA, D) 10 μM isoproterenol, E) 1mM ATP, and F) 100 μM nor-epinephrine plus 1 μM propranolol In each case the responses of oocytes injected with hippocampal membranes are compared to sham-injected ‘control oocytes’ recorded at the same time.