Characteristics Of Membrane Current Induced By Diverse Types Of Excitory Amino Acide Receptors The Mutual Influence Of Membrane Current Induced By Receptors With Diverse Coupling Mode In Xenopus Oocytes

Total RNA was isolated from adult rat brain by acid guanidnium thiocyanate-phenol-chloroform(AGPC)method.mRNA was isolated from total RNA by oligo(dT)-cellucose chromatography.mRNA was then micro-injected into Xenopus oocytes to express inotropic glutamate receptor (iGluRs) and TYPE I metabotropic glutamate receptor(TYPE I mGluRs ) .The membrane current induced by the expressed iGluRs and TYPE I mGluRs was measured with two-microelectrode voltage clamp technique by fast cell flow with KA and QA. 100 i? M KA induced first a peak current and then a slowly descending current ,at last to desensitize.The maintained time is 37.57mm. 2 1~i M QA induced a disciplinary calcium oscillation. The maintained time is 6.72?1 .33mm. The maintained time of membrane current induced by KA and QA were shorted as increasing agonist concentration. With the same method,we fast-cell-flowed with TYPE III mGluR agonist L-SOP to measure the membrane current induced by L-SOP. 0.8mM L-SOP induced a kind of disciplinary oscillation a while after flowing with L-SOP.The oscillation maintained time was 20.17?.47 minutes.The maintained time was shorted as increasing agonists concentration.The oscillation can be antagonized by TYPE I mGluR antagonistP3. It suggested that niGluR agonist LOP act not only on TYPEJJI,but also on TYPE I mGluRs. Double-cross desensitization of membrane current induced by QA and Carb was observed.The desensitization of membrane current induced by QA inhibited membrane current induced by Carb in the same Xenopus oocytes.Desensitization of membrane current induced by Carb can also inhibit membrane current induced by QA. With the same method,the double -cross desensitization of membrane current induced by QA and KA ,QA and L- SOP,KA and L-SOP was observed.These results suggested that herterologous desensitization of these receptors may be related to PKC.In cells with many receptors,there may be broad mutual influence among receptors.