[Effects of Bay K8644 and nifedipine on L-type Ca2+ channels in hypothalamic neurons of rats]

To investigate the effects of Bay K8644 and nifedipine on L-type of Ca2+ channels in hypothalamic neurons, the cell-attached patch-clamp technique was used to record Ca2+ current from isolated neurons. The results showed that the averaged open time and NPo were markedly increased by Bay K8644, but had no effect on channel conductance. Nifedipine, on the contrary, had an inhibitory effect on the L-type Ca2+ channels.

Statistical issues in the analysis of quantitative traits in combined crosses

We consider some practical statistical issues in QTL analysis where several crosses originate in multiple inbred parents. Our results show that ignoring background polygenic variation in different crosses may lead to biased interval mapping estimates of QTL effects or loss of efficiency. Threshold and power approximations are derived by extending earlier results based on the Ornstein-Uhlenbeck diffusion process. The results are useful in the design and analysis of genome screen experiments. Several common designs are evaluated in terms of their power to detect QTL.

[Effects of temperature on the open-channel density of delayed rectifier K+ channels in hypothalamic neurons]

AIM AND METHODS

To observe the effect of temperature on multi-order open of delayed rectifier K+ channels in hypothalamic-neurons by cell-attached mode of patch-clamp technique.

RESULTS

With temperature raising, the probability of open-channel recording increased, multichannel open occurred. The density of open - channel on membrane of 32 degrees C, 37 degrees C and 39 degrees C was 0.71, 1.22 and 1.82 channels/microm2 respectively (P < 0.05).

CONCLUSION

More Ik of hypothalamus opened with temperature raising, this benefited to the body temperature regulation of neurons in hypothalamus.

[Clinical analysis of facial nerve palsy in middle ear and mastoid surgery in 23 cases]

OBJECTIVE

To investigate the cause, the prevention and the therapy of facial nerve palsy(FNP) which induced by the operation of middle ear and mastoid surgery.

METHOD

A series of 1032 cases undergone middle ear and mastoid surgery were reviewed between 1976 and 1991.

RESULT

23 cases FNP were identified. All were incomplete and peripheral. 13 cases of them were performed decompression of facial nerve. 6 cases were cure, 4 cases on the mend and 3 cases no effect after operation. 10 cases were treated by conservation, 5 cases were cure, 3 cases on the mend and 2 cases no effect.

CONCLUSION

If the facial paralysis occurs during the operation, which means that facial nerve is damaged, except hard-stuff reason. Exploration should be done at once. If facial paralysis occurs later, conservative therapy should be selected at first. If facial paralysis is still not on the mend 1 month of postoperation, one should be done exploration of facial nerve.

Production and application of LPA polyclonal antibody

By using colloidal gold as a hapten carrier, a kind of antibody against lysophosphatidic acid (LPA) was developed and used to successfully detect 500 ng/mL LPA in dot immunogold filtration assay. Such application of the LPA antibody could offer us a way to diagnose ovarian cancer at its early stage.

Properties of acetylcholine receptor ion channels in the acutely dissociated neurons of the marginal division in the rat striatum

Cell-attached mode of patch clamp technique was employed to investigate the properties of acetylcholine (ACh)-induced ion channels in acutely dissociated neurons from the marginal division (MrD) of rat striatum. Two types of conductance states (25 pS and 60 pS) were recorded. The 25 pS channel (more than 80%) was the main type in the neurons of MrD and was described here. The amplitudes of inward currents increased with hyperpolorization and the reversing potential was about 0 mV. Both single short opening and long burst openings were observed in MrD neurons. Two-time constants of these two kinds of ion channels are 0.29 ms, 1.84 ms and 1.96 ms, 18.24 ms, respectively. Average close time can be fitted with two exponential functions, the two time constants are 1.7 ms and 54 ms. Probability of channel opening is about 0.012 and no voltage-dependence was found. The properties of reversing potential, voltage-independence and the form of agonist to the ion channels indicated that the recorded channel currents flow through AChR channels. The mAChR is involved in slow synaptic transmission and Ach can not induce the opening of mAChR ion channel. The binding site of ACh to AChR and the nAChR ion channel are the same protein, ACh can only activate nAChR ion channel directly. Therefore, the recorded ion channels in the present study are nAChR ion channels. The results suggest that nAChR ion channels exist in the neurons of MrD and the MrD probably is involved in learning and memory mechanism of the brain.

Experimental study and mechanism analysis on bioeffects by nanosecond electromagnetic pulses

The athermal bioeffects caused by nanosecond electromagnetic pulses with body cells was studied by using a broad band transverse EM-wave cell (BTEM CELL). The experimental system and preliminary mechanism analysis were presented.

[Effects of K+ channel openers on voltage-dependent K+ channel behavior in airway smooth muscle of guineapig]

In order to determine whether the K+ channel openers (PCOs), which are suggested to open K+ channels and to relax bronchial smooth muscle, would directly activate voltage-dependent K+ channels, single channel currents were studied on cell-attached and inside-out patches of smooth muscle acutely dissociated from bronchi of guinea-pig. The resting membrane potentials measured in whole-cell recording configuration showed no difference with control when cromakalim and lemakalim were applied extracellularly, which, however increased the conductance values of K+ channels with depolarization from 75.2 +/- 5.1 pS to 85.9 +/- 11.8 pS and 82.1 +/- 5.5 pS, respectively. The channels kinetics were also affected by PCOs. Mean open time (tau o) and open probability increased, in which the effects of lemakalim was stronger than that of cromakalim. Both PCOs elicited the multichannel activities in some patches. It is suggested that PCOs could evoke K+ channels with depolarization and stimulate K+ efflux, which may affect the excitability of muscle cells.

[Changes of K+ channel behaviors in airway smooth muscle from asthmatic guinea-pigs]

OBJECTIVE

To observe asthma-induced changes of single K+ channel behaviors in acutely dissociated airway smooth muscle of guinea-pig.

METHODS

The resting membrane potential (MP) was measured in whole-cell recording configuration. The elementary currents flowing through single K+ channel were recorded in cell-attached patches.

RESULTS

The properties in asthmatic group were as follows: (1) MP was decreased from -70.3 +/- 3.5 mV to -62.8 +/- 5.6 mV. (2) In the same depolarization conditions, the amplitudes of currents decayed and conductant values were decreased with significantly difference (about 51%) from the values obtained from the control group. (3) Open time constants of fast- and slow-open states shortened markedly to 25% and 7% of controls respectively. Shut time constants were prolonged. (4) Open probability showed voltage-dependence and was decreased in the same voltage range.

CONCLUSIONS

Asthmic airway hyperreactivity-related kinetic properties of K+ channel deficits, which may result a reduced threshold of excitation.

[Single channel properties of NMDA receptors in cortical neurons]

The cell-attached and inside-out configurations of the patch-clamp techniques were used to investigate single channel properties of NMDA receptors in cultured intact neurons mechanically isolated from rat cereberal cortex. Recordings were made in Mg(2+)-free solutions. A channel, with a conductance of 35 pS was studied in detail with either NMDA or L-aspartate in the patch pipette. NMDA channels were permeable to Na+ K+, but not to Cl-, the mean open times and open probabilities of these channels were decreased with increasing hyperpolarization. Distributions for the open times, closed times and burst durations required two-component fits. Channel openings were suppressed by APV. When Mg2+ was included in the pipette, the mean open times were significantly diminished in a concentration- and voltage-dependent manner. Decreasing the bath temperature prolonged channel open times and decreased current amplitudes. The results indicate that there is an intrinsic voltage dependence of NMDA channel kinetics in the intact neurons, suggesting that the normal function of the NMDA channel may be dependent on some intracellular biochemical processes.

[Changes in the functional characteristics of acetylcholine activated channels of hippocampal neurons at different periods of culture]

Patch-clamp technique was used to examine activation of single acetylcholine receptor channels of hippocampal neurons of neonatal rat at different periods of culture. The conductance values showed substantial variation from patch to patch. Some of channels have the same conductance but are kinetically different. Changes in the electrophysiological behaviour of ACh-evoked channels were dependent on the duration of culture. In the earlier period (1-2 days), the 20-pS state was predominant. Isolated short openings were much more common with mean open times usually less than 2.0 ms. In the late period of culture (18-21 days), the 31-pS state was predominant. The channel openings displays either as single events (tau o1, 0.35 ms; tau o2, 1.29 ms) or as bursts of events (tau b1, 1.15 ms; tau b2, 9.6 ms) in different patches. However, 20-pS state in the late period of culture could also be observed mostly as constituting events during the long burst.