Analysis of thirst mechanisms: osmosis and sodium sensing

口渴感是通过刺激口渴中枢（包括脑室周围器官）而引起的。通过使用膜片钳记录，从小鼠切片制备记录电活动。在电流钳模式下，高渗刺激使SFO神经元去极化。30 mM NaCl刺激的去极化幅度大于60 mM甘露醇刺激的去极化幅度。在电压钳位模式下，相同的刺激诱导内向电流。内向电流也较大的NaCl比甘露醇。对于突触后电流，同样的高渗刺激使EPSC的频率增加，IPSC的频率降低。突触电流的增加和减少也在NaCl中比甘露醇更大。它们的突触电流幅度不受影响。提示SFO神经元对高渗和钠离子均有感觉，且钠离子感觉上级渗透压感觉。

Thirst sensation is induced by stimulating the thirst center, including the circumventricular organs. The electrical activities were recorded from mouse slice preparation, by using patch clam recordings. SFO neurons were depolarized by hypertonic stimulation, under current clamp mode. The depolarization amplitude in the 30 mM NaC1 stimulation was large than that in the 60 mM mannitol stimulation. The same stimuli induced inward currents under voltage clamp mode. The inward currents were also larger in the NaC1 than mannitol. As for postsynaptic currents, the frequencies of EPSCs were increased and those of IPSCs were decreased by the same hypertonic stimuli. The increment and decrement in synaptic currents were also larger in the NaC1 than mannitol. The amplitude of their synaptic currents was unaffected. There suggest that SFO neurons sense to both hypertonicity and sodium ions and the sodium sensing is superior to the osmotic perception.