ABSTRACT
The conditions of color-reaction of boric acid with 1-(2-hydroxy-3-methoxybenzylidence-amino)-8-hydroxynaphalene-3-6-disulfonic acid in buffer medium of ethamine at pH 6.5 were studied in the assy.The maximum absorption wavelength of this coordination compound was 420 nm.The coordination reaction showed a good linear relationship at the concentrations of boric acid of 0.4～0.6 mg/L.The detection limit and molar absorptivity (ε) was 0.08 mg/L and 4.6×104 L/(mol·cm) respectively.This method presented perfect selectivity under the existence of EDTA solution,had been successfully applied in the determination of boric acid in natural mineral water for drinking.
ABSTRACT
Objective To study a rapid method for determination of trace formaldehyde in drinking water by oscilloscopic polarography.Methods In the base solution of0.01mol/L H 3 PO 4 ,the reaction product of formaldehyde and phenylhydrazine hydrochloride on the drop mercury electrode revealed a sensitive second order derivative polarographic wave at a pick electric potential-0.76V(VS?SCE).The optimum conditions and interference by other coexisting ions were analyzed.Results The de-tection limit,linear range,recovery rate,relative standard deviation(RSD)of the method were0.002mg /L,0.005-0.25mg /L,94.0%-103.0%,and0.05).Conclusion The method was simple,rapid,sensitive and highly specific.The analytical speed was about 50-60samples /h,which was suitable for the determination of trace formaldehyde in drinking water.
ABSTRACT
Picrotoxin is an anatagninst of gamma-aminobutyric acid, which is an internal inhibition-transmitter in the central nervous system, Picrotoxin exerts a biphasic action on the blood pressure and heart rate in rats and cats in vivo. That is to say, in the initial stage, picrotoxin can lower the blood pressure and heart rate, and then an elevation of these two even above the original level can be observed, up to the present, from the authors limited literature, there has been no report dealing with the problem whether picrotoxin can act on an isolated heart directly.In this study, the heart of a frog was isolated and routine intubation of the heart was done for its perfusion. Physiological polyconduction instrument was inserted through a mechanical transducer to record the heart rale and myocardial contractility. A suspending glass microelectrode coupling with a microamplifier is used to record the action potential of the ventricular myocardium. Real time analysis of all the data was accomplished with a microcomputer. The dosages of picrotoxin used were 1,5, 3.0, 6.0, and 12.0 mg per kilogram of body weight.It was found that picrotcxin can directly act on the isolated frog heart. The results were as follows.1 ) Picrotoxin exerts inhibition on the special conduction system of the heart,and the A-V node and venous sinus are very sensitive. Complete or partial transmission block can be induced.2 ) It can elicit clearly a fall of the heart rate but no biphasic action can berevealed. 3) It can reduce the myocardial contractility, suggesting that the calciuminflow during the functioning period of the action potential is effected. 4 ) It can reduce the amplitude of the action potential but no effect on themaximal depolarization speed is observed, suggesting that picrotoxin islikely to affect the level of resting potential but not the action potentialin the depolarized period.
ABSTRACT
The effects of intramuscular or intracerebroventricular injection of penta-gastrin(PG) on the action potential amplitude (APA) of the myocardial cells and the heart rate(HR) were studied. The results were as follows:1 ) Injection of 10?g/10?l of PG into one of the lateral ventricles of the ratfailed to produce any effect on APA or HR. When the dosage of PG was doubled(20?g/10?l), then HR could be slowed down significantly (P
ABSTRACT
This paper is to introduce our newly designed driving system used to push a microelectrode forward into the recording position in animal experiments. The instrument consists of two parts: 1. the hydraulic fine manipulator and 2. the holding mechanism and the secrew driving device of the microelectrode.Carefully pass a long glass shaft microelectrode through a stainless steel guide tube. Both the microelectrode and the guide tube are fixed on the frame of the instrument with two holding mechanisms. The frame is then connected to the chassis of the instrument which has previously been embedded in the skull of the experimental animal. Turn the screw driving device and both the microelectrode and the guide tube are moved forward. Stop turning when the guide tube penetrates the dura. Then the hydraulic fine manipulator is used to push the microelectrode into the recording position.A long glassshaft microelectode produces little injury to the brain tissue, thus it facilitates the repeated experiments on animals. The chassis of the driving system is implanted into the skull of the experimental animal with stereoscopic technique and its relative position with the brain tissue can not be changed during experiment. Slight movement of the animal head will in no way interfere with the recording.
ABSTRACT
Experimental methodssintraperitoneal injection of diazepam,r-aminobutyric acid (GABA) receptor antagonist (picrotoxin) and GABA synthesis inhibitor (iso-niazid) ;the pain threshold and serotonin ( 5 -HT) content in the brain are measured with spectrofluorometry.The effect of diazepam on ACTH analgesia (AA) is abstracted and the possible mechanisms of diazepam effect are studied.Results: diazepam increases the effect of AA.picroloxin and isoniazid reduce it and antagonize the analgesia effect of ACTH; diazepam increases the content of 5-HT in hipocampus,hypothalamus and midbrain;diazepam + ACTH increases,more than AC-TH or diazepam singly,the level of 5-HT in the 3 brain regions; picrotoxin and isoniazid reverse the effect of diazepam and ACTH on the content of 5-HT in the 3 brainsites; potentiation of diazepam on AA is antagonized by naloxone and atropine.