FMRFamide Modulates Outward Potassium Currents In The Olfactory Sensory Neurons Of Mouse

Objective: To rudiment explore the conduction mechanism of olfaction,we investigate the modulation of FMRFamide (Phe-Met-Arg-Phe peptides)on outward potassium currents of monse olfactory sensory neurons. Methods:The olfactory sensory neurons were be isolated from olfactory mucous ofKumming mouse using enzymatic digestion and mechanical isolation. Andthe olfactory sensory neurons were identified from their particular shapes.The olfactory sensory neurons, which were good state, were used towhole-cell patch clamp technique. In order to block the inward sodiumcurrents and the calcium currents, TTX and CdCl₂ were added to the bathsolutions. So the only outward potassium currents were recorded in ourexperiments. The FMRFamide was added to the extracelluar solution withfinal concentration of 5μm. In order to record the changes of outwardpotassium currents, different protocols were set in this experiment. Thecurrents were amplified and filtered by patch-clamp amplifier (Axopatch200B), then imported into computer, pCLAMPS.1 software was used torecord and analyze the data. We studied the effects on the peak current andthe maximum current density and voltage dependent activation dynamics ofI_K in the mouse olfactory sensory neurons membrane, with 5μmconcentration. Numerical summary results are reported as a mean, plus or minus the sample standard deviation (mean±S.D.). Statitiscal comparison wasmade using paired t test in SPSS11.0 software, with p＜0.05 consideredstatistically significant. Results: Inward sodium currents and outwardpotassium currents were recorded in mouse olfactory sensory neurons. Theoutward potassium current of mouse olfactory sensory neuron was composedof transient potassium current (I_A) and delayed-rectifier potassium current(I_K). I_K were delayed activated and not inactivated and I_A were rapidlyactivated and inactivated. The maximum current amplitude and maximumcurrent density of I_K were increased by FMRFamide with 5μm concentrationin the bath solutions, but the activation dynamics of I_K was not changed.Conclusions: (1) The olfactory sensory neurons with good state can beisolated from Kunming mouse using enzymatic digestion and mechanicalisolation. The neurons can be used to whole-cell patch clamp technique. (2)The maximum current amplitude and maximum current density of I_K wereincreased by FMRFamide in bath solutions. (3) The activation dynamics of I_Kwere not changed by FMRFamide. FMRFamide prolonged the course ofdepolarization and repolarization and inhibited the excitation of mouseolfactory sensory neurons through the changes of maximum currentamplitude and maximum current density of I_K. So the amide modulated theolfaction.