[Application of capillary non-gel sieving electrophoresis to the analysis of short tandem repeat in phenylalanine hydroxylase gene and gene diagnosis of phenylketonuria]

OBJECTIVE

To establish a sensitive, accurate and reliable method for analysis of short tandem repeat (STR) markers for gene diagnosis, capillary electrophoresis (CE) was used for analysis of a polymorphic tetranucleotide (TCTA)n in intron 3 of the phenylalanine hydroxylase (PAH) gene.

METHODS

Capillary non-gel sieving electrophoresis (CNGSE) system was used to analyze PCR products of PAH STR among 61 normal Chinese individuals and 6 phenylketonuria (PKU) families.

RESULTS

The PCR fragments that differ 4 bp from each other were well separated by CNGSE. Ten alleles were identified, with a continuous distribution from 224 bp to 260 bp. The largest allele (260 bp) was first detected in Chinese population. The alleles frequencies were calculated and PIC is 0.738. The genotypes of PAH STR of total 80 Chinese people were also analyzed and the heterozygosity is 75%. We used this procedure to PAH gene linkage analysis in 6 PKU families, in which pathogenic gene could be affirmed in 3 families, including one case of prenatal diagnosis.

CONCLUSIONS

In comparison with denaturing polyacrylamide gel electrophoresis, CE is an accurate, rapid, automatic and with high resolution analytical tool. CE in combination with PCR is a hopeful technique and might be widely used for gene diagnosis of genetic diseases in the future.

[Influence of mannitol additive on DNA separation by capillary non-gel sieving electrophoresis]

Polymer solutions with high concentration were employed as sieving buffer in order to obtain satisfactory separation of smaller DNA fragments with length of less than 1,000 base pairs. The concentrated polymer solution had very high viscosity, which was difficult to be pumped into or out of the capillary. Mannitol additive can enhance the sieving ability of hydroxy-propylmethylcellulose (HPMC) solution in a Tris-Borate-EDTA background electrolyte. With the existence of mannitol, good separation of PGEM-3Zf(+)/Hae III was able to be obtained in a less concentrated HPMC solution with relatively low viscosity. The optimum mass concentration of mannitol was investigated and it was found that 60 g/L mannitol could give the best results. Mannitol chain could be formed through hydrogen bond among mannitol, HPMC and borate. This kind of mannitol chain shaped the network and decreased the pore size, so the separation was greatly enhanced.

[Breathing control of patients with obstructive sleep apnea syndrome (OSAS) during sleep]

OBJECTIVE

It is assumed that reduced ventilatory control function during sleep may be one of the mechanisms resulting in obstructive sleep apnea syndrome (OSAS), but the breathing drive has never been measured in patients with OSAS during sleep.

METHOD

P0.1, delta P0.1/delta SaO2, delta VE/delta SaO2, delta P0.1/delta PaCO2 and delta VE/delta PaCO2 in sixteen patients with severe OSAS were measured via nasopharyngeal tubes connected with nasal mask to maintain upper airway patent, during wake and NREM I + II, NREM III + IV, REM sleep stages, and the same parameters in eleven normal subjects, non-snorers were also measured, by nasal mask as control.

RESULT

(1) During wake: P0.1 in all the OSAS patients was remarkably higher than that of the normal subjects (P < 0.05), but there was no difference in delta VE/delta SaO2, delta P0.1/delta SaO2, delta VE/delta PaCO2 and delta P0.1/delta PaCO2 between the two groups (P > 0.05). (2) The above parameters measured during sleep compared with that measured during wake: In NREM I + II and NREM III + IV, normal subjects showed no significant decrease in P0.1, delta P0.1/delta SaO2, delta P0.1/delta PaCO2 (P > 0.05), but delta VE/delta SaO2 and delta VE/delta PaCO2 decreased significantly (P < 0.05). In REM1 P0.1 maintained the same level as that during wake, but both hypoxic and hypercapnic responses decreased remarkably (P < 0.05). In the OSAS patients, P0.1 decreased during NREM I + II and REM sleep (P < 0.5), but not during NREM III + IV (P > 0.05). delta VE/delta SaO2, delta P0.1/delta SaO2, delta P0.1/delta PaCO2 and delta VE/delta PaCO2 decreased markedly during all sleep stages (P < 0.01). (3) From wake to sleep, delta VE/delta SaO2 decreased by 51.6 +/- 30.4% (Mean +/- SD) in the OSAS patients vs 33.6 +/- 26.0% decreased in the normal subjects; delta VE/delta PaCO2 decreased by 56.9 +/- 25.5% in OSAS vs 40.8 +/- 17.5% in the normal subjects; The hypoxic and hypercapnic responses in OSAS patients decreased much more than those in the normal subjects during sleep (P < 0.05).

CONCLUSION

This is the first study to measure the hypoxic and hypercapnic responses successfully in OSAS patients during sleep. It was found that the breathing drive was significantly reduced in sleeping OSAS patients, which may play an important role in the development of OSAS, possibly through the reduced action upon the dilators causing the upper airway in predilection for collapse.

[The study on in vivo erythropoietin gene transfer for treatment of renal anemia in animal model]

To explore the possibility of gene therapy to renal anemia, the receptor mediated erythropoietin (EPO) gene transfer in vivo had been tested. EPO gene was inserted to an EBV replicon expression vector to form the plasmid pEPO, Renal anemia rat had been induced by feeding with adenine, and 450 micrograms of the pEPO was delivered by perfusion into the rat peripheral circulation in the form of soluble DNA/galactosylate histone complex. 13 days after injection, the number of peripheral red cells was counted and the concentration of hemoglobin was measured. The results demonstrated that symptom of anemia had been significantly improved(P < 0.01), when compared with that of the control test. (the red cell number was 492 vs 409, and the hemoglobin was 11.4 vs 9.1).

Synteny with rice: analysis of barley malting quality QTLs and rpg4 chromosome regions

The barley (Hordeum vulgare L.) chromosome 1 centromere region contains two adjacent overlapping quantitative trait loci (QTLs) for malting quality traits, and the chromosome 7L subtelomere region contains the stem rust (causal agent Puccinia graminis f.sp. tritici) resistance gene rpg4. To facilitate the saturation mapping of these two target regions, a synteny-based approach was employed. Syntenic relationships between the barley target regions and the rice (Oryza sativa) genome were established through comparative mapping. The barley chromosome 1 centromere region was found to be syntenic with rice chromosome 8 and parts of rice chromosomes 3 and 10. A 6- to 15-fold difference in genetic distance between barley and rice in the syntenic region was observed, owing to the apparent suppressed recombination in the barley chromosome 1 centromere region. Barley chromosome 7L was found to be syntenic with rice chromosome 3. The establishment of synteny with rice in the two target regions allows well-established and characterized rice resources to be utilized in fine mapping and map-based cloning studies.Key words: genome synteny, quantitative trait loci, QTL, disease resistance gene, Triticeae.

[Synthesis and preliminary study on cleavage activity of ribozyme to hepatitis B virus preS2 gene in vitro]

In this paper, a multi-target hammerhead ribozyme gene was synthesized directed against 110, 122 and 132 sites of nucleotide of HBV preS2 gene. The target gene fragment was cut from HBV genome containing plasmid pCP10. Both of the ribozyme and the target gene fragments were cloned into pGEM3Zf(-) plasmid and sequenced by dideoxy chain termination method. The transcription of both gene fragments was performed in vitro utilizing T7 RNA promoter in pGEM3Zf (-) plasmid. The cleavage activity of ribozyme to substrate was confirmed in vitro. For further evaluating intracellular function of ribozyme, two ribozyme-retroviral recombinant plasmids with different promoter type pDOR-ripe and tRNA-ripe were constructed. Pseudo-virus was collected through routine packaging procedure and transduted into 2.2.15 cells. RIA data showed a stable inhibition of pHSA-R antigen expression to the lowest extent of 41.01% +/- 4.16 and the highest extent of 51.45% +/- 4.57 within 4 weeks after transduction. No influence, however, on HBsAg and HBeAg expression was demonstrated after ribozyme gene transfer.

[Cloning and expression of subunit genes of pertussis toxin and its immunological evaluation]

OBJECTIVE

To clone the gene encoding pertussis toxin (PT) from Bordetella Pertussis CS strain and five genes encoding subunits of PT, to investigate the possibility of expressing the genes encoding for mature methionyl subunits of PT in insect cell and to evaluate the immunological characteristics of recombinant subunits.

METHODS

The genes encoding for PT and its subunits were cloned by PCR and confirmed by restriction enzyme digestion and Southern blot. Using recombinant baculovirus technology, the recombinant subunits were expressed in Sf9 insect cells and analyzed by immunofluorescence assay. The immunological properties of recombinant subunits were analyzed by ELISA.

RESULTS

The genes encoding for PT and its subunits were cloned and expressed in Sf9 cells. The level of specific antibodies against nature PT induced by five recombinant subunits polymerized was higher than that unpolymerized and polymerized by four recombinant subunits (without S1) in mice. The results indicate that PT subunits had weak ability to induce specific antibodies against PT, and also anti-nature PT sera had poor recognition to PT subunits.

CONCLUSION

The ability of PT to induce specific antibody is conformation dependent of intact PT, and antibody induction domains are located dominantly in S1 subunit of intact PT.

[Molecular biological evidence for the genetic stability of in vivo passaged doxorubicin resistant cell line S-180R]

OBJECTIVE

To assess the genetic stability of doxorubicin resistant sarcoma 180 cell line(S-180R) after in vivo passages.

METHODS

Flow cytometry, Southern blot, Northern blot and RT-PCR were used to examine genes and molecules related to drug resistance.

RESULTS

The drug-efflux of S-180R was nearly 100-fold as high as that of the parental cells. The ratio of half peak width to peak height was 0.23 as compared to 0.56 measured two years before when the S-180R cell line was initially established. The mdr-1 gene was significantly amplified and transcribed while the transcription of topoisomerase II alpha gene was decreased. However there was no increase in mRNA expression of the multidrug resistance associated protein(MRP).

CONCLUSION

Compared with the initially established S-180R, its resistance to doxorubicin is not only maintained but in fact has been increased since in vivo passage for 2 years. The major mechanism is amplification and over-expression of mdr-1 gene, but decreased topoisomerase II alpha also contributes. S-180R is an ideal experimental model for the study of doxorubicin resistance and its reversion.

[Orbito-facial reconstruction after extensive anterior skull base, head and neck resection using a rectus abdominis musculocutaneous flap]

In response to the recent advances in aggressive excision of skull base and head and neck malignancies, a more sophisticated method primary reconstruction has been developed using a craniofacial techniques for preservation of postoperative quality of life. We have developed an inferior pedicled rectus abdominis musculocutaneous flap with rib cartilages for reconstruction of the orbito-facial region. The advantages of this flap are as follows; 1) Simultaneous flap elevation in a supine position is possible, 2) Easy, versatile and reliable flap adjustment can be made for complicated space defect, 3) Curvature of the ipsilateral rib cartilages is suitable for inferior orbital rim, 4) Lower risk of pleura laceration as compared with a superior pedicled flap. In the past 5 years, the composite free flaps have been applied for 3 cases of hemi orbito-facial defect, with better results than in previous cases. Our technique for the flap application in a representative case is illustrated.

[Anti-virus effect of hepatocyte stimulating substance (HSS) on duck hepatitis B virus in vivo]

We used one day old Beijing ducklings infected by duck hepatitis B virus as experimental model to observe anti-virus effect of HSS. Beijing ducklings hatched within one day were injected intravenously with duck hepatitis B virus (DHBV). Positive DHBV-DNA in ducklings' sera were detected 7 days later. Serum samples were obtained from all ducklings before, during and after drug treatment at different times and stored at -70 degrees C. The collected samples were detected DHBV-DNA by dot-blot hybridization test at the same time. The therapeutic effects were evaluated by OD value of dot-blot and by the inhibitory rate of DHBV-DNA. The results showed that HSS (with 50 mg/kg/day and 200 mg/kg/day) were effective in inhibition of DHBV-DNA during and after drug treatment, especially in the HSS group of large dosage. The inhibitory effect appeared early and high dynamic. The inhibitory rate of DHBV-DNA during and after drug treatment were higher than the NS group (P < 0.05). No inhibitory effect was observed in NS group. The hepatic biopsy showed HSS groups had milder damage than NS group, indicating that the HSS could inhibit the replication of DHBV-DNA in Beijing ducklings.

pH-dependent changes of nitric oxide, peroxynitrite, and reactive oxygen species in hepatocellular damage

Low arterial blood pH and sustained nitric oxide (NO) production are critical parameters in inflammatory events such as sepsis, and appropriate treatment is still under debate. Because the stability of nitrogen and oxygen intermediates is dependent on the surrounding pH, we investigated whether the relationship among NO, peroxynitrite (ONOO-), and reactive oxygen species production also depends on the pH value, particularly with respect to their effects on hepatocellular damage. Our studies demonstrate that the extracellular pH influences NO and hydroxyl radical (OH) production in hepatocytes. Acidification (pH 7.0) of the medium revealed a significant increase (P < 0.05) of OH-like radicals, enhanced hepatocellular damage, and a sharp drop in cellular glutathione (GSH) content compared with levels measured at physiological or alkaline pH conditions. Furthermore, inhibition of NO synthesis at all pH conditions resulted in decreased NO production and cellular GSH levels but a simultaneous increase of OH-like radicals and hepatocellular damage with a maximum seen at pH 7.0. Our results suggest that hepatocellular damage is in part regulated by the surrounding pH and that inhibition of NO synthesis at acidic conditions (e.g., in sepsis) leads to increased reactive oxygen-mediated cell injury.

Towards map-based cloning of the barley stem rust resistance genes Rpg1 and rpg4 using rice as an intergenomic cloning vehicle

The barley stem rust resistance genes Rpg1 and rpg4 were mapped in barley on chromosomes 1P and 7M, respectively and the syntenous rice chromosomes identified as 6P and 3P by mapping common probes in barley and rice. Rice yeast artificial chromosome (YAC), bacterial artificial chromosome (BAC) and cosmid clones were used to isolate probes mapping to the barley Rpg1 region. The rice BAC isolated with the pM13 probe was a particularly excellent source of probes. A high-resolution map of the Rpg1 region was established with 1400 gametes yielding a map density of 3.6 markers per 0.1 cM. A detailed physical map was established for the rice BAC fragment containing the Rpg1-flanking markers pM13 and B24. This fragment covers a barley genetic distance of 0.6 cM and a rice DNA physical distance of ca. 70 kb. The distribution of barley cross-overs in relation to the rice DNA physical distances was extremely uneven. The barley genetic distance between the pM13 marker and Rpg1 was 0.1 cM per ca. 55 kb, while on the proximal side it was 0.5 cm per ca. 15 kb. Three probes from the distal end of the pM13 BAC mapped 3.0 cm proximal of Rpg1 and out of synteny with rice. These experiments confirm the validity of using large insert rice clones as probe sources to saturate small barley (and other large genome cereals) genome regions with markers. They also establish a note of caution that even in regions of high microsynteny, there may be small DNA fragments that have transposed and are no longer in syntenous positions.

[DNA polymorphism analysis by capillary electrophoresis]

A review is given here to describe the principle and methods of gene polymorphism analysis by capillary electrophoresis (CE). DNA length polymorphism and sequence polymorphism are very important phenomena in gene molecular biology. Some practical works of gene length polymorphism analysis and sequence polymorphism analysis are listed. SSCP and HPA methods detecting gene point mutations are demonstrated. Applications of gene polymorphism analysis by CE in clinical, forensic and biological research are also discussed in this paper.

[Comparison of anti-hepatitis C virus (HCV) IgM and HCV-RNA detection in serum samples of patients with HCV infection]

Anti-HCV IgG is the routine assay for the diagnosis hepatitis C. But the method is ineffective in early detection of hepatitis C. We have detected anti-HCV IgM in hospital hepatitis C patients by Enzyme-Linked Immunosorbent Assay (ELISA) and compared the results with those of HCV-RNA and total antibody. Our studies indicate that anti-HCV IgM is detected in all hepatitis C marker positive sera. But the amount of anti-HCV IgM in HCV-RNA positive sera is significantly higher than that of in the corresponding negative sera. This subjects that anti-HCV IgM and HCV-RNA are somewhat correlated and they have different clinical interests. Anti-HCV IgM can be expected and hepatitis activities and its actual clinical interests are to be further studied.

[Drug resistance mechanism of doxorubicin-resistant human gastric cancer cells BGC-823/DOX]

To further investigate drug resistance mechanism of BGC-823/DOX, we analysed the amplication, transcription and overexpression of genes associated with drug resistance by Southern blot, RT-PCR, immunohisto clogical assay and the concentration of Doxorubicin in the cells by flow cytometry. The results showed that parent cells of BGC-823 were cell line with intrinsic drug resistance similar to the gastrointestinal tumors. Multidrug resistance was the main mechanism of drug resistance in BGC-823/DOX. There was a significant difference between the doxorubicin-resistant cells line from parent cells with intrinsic drug resistance and from parent cells without intrinsic drug resistance in drug resistance.

[Establishment and characterization of doxorubicin-resistant BGC-823/DOX of human gastric cancer cell line]

To study drug resistance mechanism of gastrointestinal tumor, doxorubicin resistant cell line of human gastric cancer, we developed BGC-823/DOX, by increasing doses of doxorubicin. We completed chromosomal analysis, double time of cell grow, cell cycle distributions, drug resistance and cross-resistance, and studied reversing drug resistance. The results showed that chromosome of BGC-823/DOX was subtriploid karyotype. Cell morphology, double time, cell cycle distributions were different from its parent cells and 6.35 times more resistant to cytotoxic action of doxorubicin, cross-resistant to VP-16. Verapamil showed modified effect on doxorubicin resistance. BGC-823/DOX with doxorubicin resistance has many characteristics of gastrointestinal tumors.

Pathological classification and diagnosis of intestinal duplication

OBJECTIVE

To determine the pathological classification and the clinical characteristics of intestinal duplication.

METHODS

Eighty-four pediatric patients with intestinal duplication were proved on operation in the last 20 years in the Second Hospital of Harbin Medical University and Harbin Children's Hospital. The pathological classifications were as follows: enteral septum type (2), parietal cyst type (9), parenteral canal type (31), parenteral cyst type (35), and solitary type (1). The clinical presentations and complications included: abdominal mass (24), illius (41), hemorrhage of digestive tract (15) and intestinal perforation with peritonitis (3). Two asymptomatic cases were discovered incidentally.

RESULTS

Among the 84 patients, 82 healed, 1 newborn complicated by intestinal fistula died of septicemia, and the other one died of toxic shock.

CONCLUSIONS

Recognizing the pathological types, common presentations and complications, and applying the corresponding examination methods timely, doctors may improve the diagnostic accuracy.

[Effects of some Chinese herbal medicine and green tea antagonizing mutagenesis caused by cigarette tar]

Anti-mutagenic effects of some Chinese herbal medicine and green tea antagonizing cigarette tar was studied with unscheduled DNA synthesis (UDS) test in human peripheral lymphocytes in order to exploit the better use of Chinese herbal resources. Results showed that Scutellaria barbata, Hedyotis diffusa wildi, Xihuangwan, green tea and tea polyphenol all had anti-mutagenic effects, to some extent. And, 125 g/L of Scutellaria barbata, 125 g/L Hedyotis diffusa wildi, 325 g/L Xihuangwan, 78 g/L green tea and 25 g/L tea polyphenol could inhibit obviously the damage to DNA in lymphocytes caused by the total particle material (TPM) extracted from cigarette tar. If the Chinese herbal medicine and green tea were injected into cigarettes beforehand, extracted TPM (containing herbal medicine and green tea) also could protect DNA in lymphocytes from damage caused by cigarette tar, to even greater extent. This result is basically consistent with other anti-mutagenesis tests.

Cloning and mapping of a putative barley NADPH-dependent HC-toxin reductase

The NADPH-dependent HC-toxin reductase (HCTR), encoded by Hm1 in maize, inactivates HC-toxin produced by the fungus Cochliobolus carbonum, and thus confers resistance to the pathogen. The fact that C. carbonum only infects maize (Zea mays) and is the only species known to produce HC-toxin raises the question: What are the biological functions of HCTR in other plant species? An HCTR-like enzyme may function to detoxify toxins produced by pathogens which infect other plant species (R. B. Meeley, G. S. Johal, S. E. Briggs, and J. D. Walton, Plant Cell, 4:71-77, 1992). Hm1 homolog in rice (Y. Hihara, M. Umeda, C. Hara, Q. Liu, S. Aotsuka, K. Toriyama, and H. Uchimiya, unpublished) and HCTR activity in barley, wheat, oats and sorghum have been reported (R. B. Meeley and J. D. Walton, Plant Physiol. 97:1080-1086, 1993). To investigate the sequence conservation of Hm1 and HCTR in barley and the possible relationship of barley Hm1 homolog to the known disease resistance genes, we cloned and mapped a barley (Hordeum vulgare) Hm1-like gene. A putative full-length cDNA clone, Bhm1-18, was isolated from a cDNA library consisting of mRNA from young leaves, inflorescences, and immature embryos. This 1,297-bp clone encodes 363 amino acids which show great similarity (81.6%) with the amino acid sequence of HM1 in maize. Two loci were mapped to barley molecular marker linkage maps with Bhm1-18 as the probe; locus A (Bhm1A) on the long arm of chromosome 1, and locus B (Bhm1B) on the short arm of chromosome 1 which is syntenic to maize chromosome 9 containing the Hm2 locus. The Bhm1-18 probe hybridized strongly to a Southern blot of a wide range of grass species, indicating high conservation of HCTR at the DNA sequence level among grasses. The HCTR mRNA was detected in barley roots, leaves, inflorescences, and immature embryos. The conservation of the HCTR sequence, together with its expression in other plant species (R. B. Meeley and J. D. Walton, Plant Physiol. 97:1080-1086, 1993), suggest HCTR plays an important functional role in other plant species.

Isolation and characterization of GT335, a novel human gene conserved in Escherichia coli and mapping to 21q22.3

As part of efforts to identify candidate genes for disorders mapped to 21q22.3, we have constructed a 405-kb cosmid contig encompassing five tightly linked markers mapping to this region. A subset of these cosmids was used to identify cDNA fragments by the method of hybrid selection. We present here the cDNA sequence of one such gene (GT335) mapping to this region. The gene is expressed as a 1.7-kb transcript predominantly in heart and skeletal muscle, potentially displays alternate splicing, and is predicted to encode a protein 268 amino acids in length. GT335 spans an estimated 13 kb of genomic DNA and is split into seven exons. Five of the six introns conform to the GT . . . AG consensus for intronic splice junctions; the sixth contains nonconventional (AT . . . AC) intronic junctions. We screened this gene for single-basepair mutations using single-strand conformation polymorphism and sequence analysis of both cDNA and genomic DNA from a number of unrelated individuals and have identified several sequence variations, two of which cause conservative amino acid substitutions. This gene is well conserved evolutionarily, with homologs identified in zebrafish and Escherichia coli, suggesting that it plays an important role in basic cellular metabolism.

[The research of radioimmunoassay using double Abs for bradykinin]

Bradykinin (BK) is a potent vasodilative substance, and plays great physiological and pathological roles in animals and human beings. To measure the quantity of BK, the radioimmunoassay (RIA) has been devised, but the traditional RIA method has certain defects, such as presence of numerows interfering factors and errors and time consuming. Now, we produce anti-BK serum in rabbits by using BK-ovalbumin conjugate as an immunogen, and the 125I labeled Tyr8-BK by using a modified chloramine-T method. High specific activity has been obtained after purification with DEAE-Sephadex A-25 column chromatography. We use the donkey anti-rabbit Ab and PEG 6000 to separate the bound from the free 125I-Tyr8-BK. The limitation range of standard curve is from 25 to 1600 pg, NSB is 3.1% affinity constant (K) is 0.8 x 10(10) L/mol, and there is no significant interference with other biological BK analogues. The blood samples are treated by adding Polybrene (inhibitor) and PEG 6000 to deposit the big serum proteins in order to reduce the disturbing substances. This method has been shown to be a sensitive, specific, reliable, simple and convenient measure of the serum BK level. By this method, the serum BK quantities in men, women and rats are respectively 1584 +/- 347 pg/ml, 1642 +/- 302 pg/ml and 1805 +/- 225 pg/ml, the recycling rate is 95%, the intergroup CV is 5.0% and outergroup CV = 9.2%.

[Effects of gossypol acetic acid on human ejaculated sperm Ca2+ influx and rat vas deferens contraction action]

It has been reported that gossypol acetic acid (GAA) inhibits sperm motility and calcium plays an important role in regulating the function of the sperm flagella. In order to explore the mechanism by which GAA inhibits sperm motility, the effects of GAA on human ejaculated sperm Ca2+ influx and isolated rat vas deferens contraction action were studied. The results showed that GAA inhibited sperm Ca2+ influx in a dose-dependent manner, and breaked the dynamic equilibrium of sperm internal and external Ca2+ gradient concentrations. It may be one of important mechanism by which GAA inhibits sperm motility. But GAA exerts no effect on the high K+ induced contraction of smooth muscle of isolated rat vas deferens. It is likely that GAA has selective action on the sperm membrane of the rats.