Effects Of GB On The Bioelectric Activity And Synaptic Transmission Of The Neurons In Celiac Ganglia Of Guinea-pig In Vitro

In applying of the intracellular bioelectric recording technique, we have observed the passive and initiative electricity character, excitatory postsynaptic potential and action potential of GB on the greater splanchnic nerve - celiac ganglia of guinea-pig in vitro. And through the perfusing with the relevant receptor blocking pharmacon, low Ca²⁺/ high Mg²⁺, and low Na⁺ .etc. Krebs solution, we have explored the possible mechanism of effects of GB on the CG bioelectric and synaptic transmission.We have observed the forms and types of CG cells and the protecting action of GB on CG cells by applying the histiocyte hematoxylin and eosin staining method. Following is the main conclusions: 1. Effects of passive electricity character of GB on CG cell membrane1.1 The mean value of resting potential of neurons of celiac ganglia (CG) of guinea pig was -61.14 ± 0.61 mV ( n = 276 ); the mean values of membrane resistance (Rm) and conductance (G) were 87.25 ± 5.48 MQandl4.80 ± 0.80 nS (n = 80 ); and the mean values of membrane capacity (Cm) and time constant (x) were 245.84 ± 27.04 pF å’Œ 1.97 ±0.21 ms(n = 80).1.2 Effects of GB on the membrane resistance (Rm) and potential of guinea-pig in vitroTo perfuse CG( n = 106 )with GB of 1 × 10^-6mol/L -10×10^-6 mol/L, the membrane potentials of 55.7% (59/106) cells weren't alerted obviously; the membrane potentials of 35.8% (38/106) cells were depolarized moderately; the membrane potentials of 8.5% (9/106) cells appeared biphasic reaction and depolarized after hyperpolarized. The depolarization and AP evoking appeared at the same time of some individual cells. The depolarization by GB were 11.30 ± 1.78 mV and 108.50 ± 9.85 ms. And 25 observed membrane resistance of CG cells, which have reaction, weren't affected obviously.1.3 The analyze to the mechanism which the membrane potentials of CG cells were depolarized by GB.To perfuse CG with low - Na+ Krebs solution, the amplitude of membrane depolarization weakened in a limited level (n = 4). To perfuse CG with TEA of K+ channel blocker, the amplitude of membrane depolarization strengthened in a limited level (n = 5), and it pointed out that GB could change the Na+,K+ permeability of CG cells, and also could make the cell depolarized. Because GB didn't affect the membrane resistance (Rm), it suggests that GB could reduce the permeability of some ions on the membrane. 2. Effects of initiative electricity character of GB on CG cell membrane2.1 The AP of CG cells of Guinea-pig in vitro induced by direct intracellular stimulating The amplitude (APA) and duration (APD) of action potentials were 58.63 ± 0.91mVand 2.15 ± 0.04 ms, The amplitude (AHPA) and duration (AHPD) of the prolonged afterspike hyperpolarization were -15.49 ± 0.30 mV and 16.90 ± 0.40 ms (n = 145).2.2 Effects of the AP of CG cells of Guinea-pig in vitro induced by direct intracellular 1 stimulatingTo perfuse CG with 1 X 10"6 6X 10'6mol/L GB (n = 33) , the firing frequency of AP of 97%(32/33) cells increased, the APA and AHPA increased; and 3% ( 1/33) AP of cells were inhibited. To perfuse CG with8X10'6 10X 10'6mol/LGB (n = 19), the firing frequency of AP of 13.1% (14/19) cells decreased, the amplitude degraded, or even were inhibited completely; and to the other 15.8% (3/19) cells, the firing frequency and the amplitude increased; and 10.5% (2/19) cells were hardly no reaction.2.3 The analyze to the mechanism of effects of the AP of CG cells of Guinea-pig in vitro induced by direct intracellular stimulatingIn the experiment, to perfuse CG with low Na+ Krebs solution, the amplitude of AP decreased fast, even disappeared; by the washing with Krebs solution, AP renewed. It shows that the amplitude of AP concerned with the density of Na+.To perfuse CG with TEA singly, the spike interval between AP was extended; To perfuse CG with low density GB, the inducing of AP increased, and the spike interval shorted. To perfuse CG with the both at same time, the inducing of AP still increased,but the spike interval kept unchanged. It shows that GB increased the possibility of the AP's firing concerned with the promotion to the K+ channels opened and the AP repolarization duration shorted. -High density GB inhibited the firing of AP, it shows the functions of GB were complicated; it maybe has the function of biphasic regulation.To perfuse CG with both GB and ACh, AP induced easily. It shows GB and ACh maybe have the function of cooperation, GB not only could act on Voltage-operated Ca2+ channels on the CG membrane in order to promote the Na+ influx, but also could act on postsynaptic chemically-operated Na+ channels in order to the synergism with ACh.To perfuse CG with both GB and Suramin of ATP receptor blocking pharmacon, it could decreased the inhibition of Suramin to AP. It shows GB could decreased the action of Suramin, and made the permeability of Na+, K+ enhanced, and AP induced easily.3. Effects of GB on the cell synaptic transmission of CG"' 3.1 The amplitude and duration of f-EPSP induced by CG cells of Guinea-pig in vitro which induced by stimulating greater splanchnic nerve were 12.55 ± 0.91 mVfP 32.70 ± 1.43 ms, the latency wasl3.10 ± 0.86ms (n = 44); the APAand APD were 65.44 ± 1.67 mV and 2.11 ± 0.06 ms, and AHPA and AHPD were -8.27±0.52 mV and 12.80 ± -1.23 ms (n = 56) .3.2 Effects of GB on the f-EPSP and AP which induced by stimulating greater splanchnic nerveTo perfuse CG with 1 X 10"6¹0 X 10"6mol/L CG (n=12), the amplitude of f-EPSP were decreased in different level. To perfuse CG with2 X 10"6mol/L GB CG (n = 22), the AP of 54.5%(12/22) cells unchanged; the firing frequency of AP of 27.3% (6/22) cells increased, the amplitude increased; 18.2% (4/22) APof cells were inhibited.3.3 The analyze to the mechanism of effects of GB on the f-EPSP and AP which induced by stimulating greater splanchnic nerveTo block the f-EPSP with low Ca2+/high Mg2+ Krebs solution, then to perfuse CG with GB, it was difficult to induce the f-EPSP; to perfuse CG with high Mg2+ Krebs...