Biomedical subjects

J G Zhuang

Publications and source records attributed to J G Zhuang.

6 recordsLinked to original sources

PubMed2000

[The studies on protective effects of SM against myocardial hypoxia/reoxygenation injury].

AIM AND METHODS: To assess the myocardial effects of Salvia Miltiorrhiza (SM) injection against hypoxia-reoxygenation injury, 31P NMR was used to trace the time courses of high energy phosphates (HEP) content and intracellular pH (pHi) of the isolated perfused rat hearts under hypoxia (30 min) and subsequent reoxygenation (40 min). RESULTS: It was discovered that SM significantly preven-ted the decrease in the myocardial HEP content during hypoxia, enhanced the recovery of myocardial phosphocreatine (PCr), adenosine triphosphate (ATP) and the PCr/Pi (inorganic phosphate) ratios during reoxygenation, and lightened the decrease of the myocardial pHi value caused by hypoxia. CONCLUSION: SM improves the myocardial energy metabolism level during prolonged hypoxia and subsequent reoxygenation and protects myocardium against hypoxia/reoxygenation injury. SM significantly attenuates acidosis during hypoxia and prevents the appearance of very acidic areas of the myocardium after reoxygenation.

Animals↗

PubMed2000

Hypoxic preconditioning upregulates KATP channels through activation of protein kinase C in rat ventricular myocytes.

AIM: To test: 1) if hypoxic preconditioning upregulates the activity of KATP channels in isolated adult rat cardiac myocytes; 2) if the upregulation involves protein kinase C (PKC). METHODS: By the whole-cell patch-clamp recording technique, KATP channel currents (IKATP) were measured in the cardiomyocytes with no pretreatment (CON), hypoxic exposure preceding reoxygenation (HPC), phorbol 12-myristate 13-acetate (PMA), and chelerythrine addition with HPC (CH + HPC), respectively. RESULTS: At 0 mV and 5 min after 2, 4-dinitrophenol (DNP) perfusion, the membrane currents for the CON, HPC, PMA, and CH + HPC were (3.5 +/- 1.9), (7.7 +/- 1.5), (7.5 +/- 3.3), (4.6 +/- 2.4) nA, respectively. Compared with the CON, the IKATP in the HPC and PMA were significantly augmented (P < 0.01) while the IKATP in the CH + HPC remained similar to the CON (P > 0.05). CONCLUSION: 1) hypoxic preconditioning stimulated the activity of PKC and markedly enhanced the activity of KATP channels in the isolated rat cardiac myocytes; 2) PKC activation was involved in the upregulation of KATP channels.

Alkaloids↗

PubMed1997

[Study model for isolated heart perfusion combined with NMR technique].

Some improvements made to overcome the difficulty in the long distance perfusion, temperature maintenance, oxygen supply and the recollection of perfused fluid were described in our Langendorff perfusion in combination of NMR technique with which the rhythmic activity of isolated rat heart can be measured as long as 90 min.

Animals↗

PubMed1993

The setting of an occupational exposure limit for phosphamidon in the workplace--a Chinese approach.

This paper describes the approach of setting an occupational exposure limit for phosphamidon, an organophosphorus pesticide, in the workplace in China. Apart from a general review of the literature relating to various toxicological studies, special emphasis has been placed on the results of a systematic occupational health survey on the workers exposed to phosphamidon. As a result of the survey, together with the literature review, a 'maximum allowable concentration' (MAC) for phosphamidon in the air of workplace is suggested as 0.02 mg m-3 but on the condition that the route of skin entry be blocked effectively. In addition, based on the description of the standard-setting process in China, a comparison has been made to the current U.K. approach.

China↗

PubMed1992

Are Tibetans better adapted?

Evidence is reviewed from our recent (1987-1991) investigations which demonstrate better high-altitude adaptation among Tibetans than in acclimatized newcomers or other lifelong high-altitude residents. Characteristics of oxygen transport contributing to the Tibetans' remarkable exercise performance are described.

Acclimatization↗

PubMed1991

Increased vital and total lung capacities in Tibetan compared to Han residents of Lhasa (3,658 m).

Larger chest dimensions and lung volumes have been reported for Andean high-altitude natives compared with sea-level residents and implicated in raising lung diffusing capacity. Studies conducted in Nepal suggested that lifelong Himalayan residents did not have enlarged chest dimensions. To determine if high-altitude Himalayans (Tibetans) had larger lung volumes than acclimatized newcomers (Han "Chinese"), we studied 38 Tibetan and 43 Han residents of Lhasa, Tibet Autonomous Region, China (elevation 3,658 m) matched for age, height, weight, and smoking history. The Tibetan compared with the Han subjects had a larger total lung capacity [6.80 +/- 0.19 (mean +/- SEM) vs 6.24 +/- 0.18 l BTPS, P less than 0.05], vital capacity (5.00 +/- 0.08 vs 4.51 +/- 0.10 1 BTPS, P less than 0.05), and tended to have a greater residual volume (1.86 +/- 0.12 vs 1.56 +/- 0.09 1 BTPS, P less than 0.06). Chest circumference was greater in the Tibetan than the Han subjects (85 +/- 1 vs 82 +/- 1 cm, P less than 0.05) and correlated with vital capacity in each group as well as in the two groups combined (r = 0.69, P less than 0.05). Han who had migrated to high altitude as children (less than or equal to 5 years old, n = 6) compared to Han adult migrants (greater than or equal to 18 years old, n = 26) were shorter but had similar lung volumes and capacities when normalized for body size. The Tibetans' vital capacity and total lung capacity in relation to body size were similar to values reported previously for lifelong residents of high altitude in South and North America. Thus, Tibetans, like North and South American high-altitude residents, have larger lung volumes. This may be important for raising lung diffusing capacity and preserving arterial oxygen saturation during exercise.

Adult↗