Objective\ To test the effect of hypothermia on Na+/H+ exchange, activated by shrinkage and cytoplasmic acidosis. Method\ Amiloride-sensitive Na+ influx in guinea pig red cells was traced with isotope 22Na an...Objective\ To test the effect of hypothermia on Na+/H+ exchange, activated by shrinkage and cytoplasmic acidosis. Method\ Amiloride-sensitive Na+ influx in guinea pig red cells was traced with isotope 22Na and intracellular Na+ concentration was measured by emission flame photometry. Result\ Amiloride-sensitive Na+ influx decreased linearly as a function of temperatures (about 37℃) in shrunken cells, but increased in acidified cells. The up-regulation of acid-induced Na+/H+ exchange by elevated temperature was enhanced by hypo-osmolarity. Less sensitivity of intracellular H+ site at 41℃ may be the mechanism for the inhibition of shrinkage-induced Na+/H+ exchange by elevated temperature. Heating-mediated explosive increase in the activity of acid-induced Na+/H+ exchange may be due to enhanced extracellular Na+ sensitivity and lower intracellular pH caused by acidic metabolites. Acid-induced Na+/H+ ewxchange contributes to cytoplasmic Na+ accumulation. Conclusion\ These two modes of Na+/H+ exchange with different response to elevated temperature may play different roles in the cellular pathogenesis of heatstroke.展开更多
Background Control of hypersecretion of certain hormones is one of the key targets in the treatment of pituitary adenomas. RNA interference has been shown to inhibit protein expression, and thus it may represent a pro...Background Control of hypersecretion of certain hormones is one of the key targets in the treatment of pituitary adenomas. RNA interference has been shown to inhibit protein expression, and thus it may represent a promising method for the treatment of pituitary adenomas. In the present study, transfection efficiency of small interfering RNA （siRNA） was optimized in human prolactinoma cells. Methods First, a method was optimized to extract highly purified human prolactinoma cells in vitro. The extracted cells were verified to retain the physiological features of prolactin （PRL） secretion. Second, three conditions for siRNA transfection were tested by the evaluation of transfectfon efficiency and cell viability. The proper transfection condition was verified for human prolactinoma cells. Third, the siRNA for prolactin was transfected into the human prolactinoma cells, and the suppression of PRL mRNA was evaluated by quantitative real-time reverse transcription-PCR. Results The siRNA of 100 pmol with Lipofectamine 2000 of 5 μl for 1×10^6 cells was proved preferable, with transfection efficiency being 53.3% and cell viability being 69.7%. In the preliminary experiment the siRNA against PRL decreased the mRNA of PRL by 34.0%. Conclusion It is possible to inhibit hormone hypersecretion by RNA interference, that may eventually enable therapeutic siRNA drugs developed.展开更多
文摘Objective\ To test the effect of hypothermia on Na+/H+ exchange, activated by shrinkage and cytoplasmic acidosis. Method\ Amiloride-sensitive Na+ influx in guinea pig red cells was traced with isotope 22Na and intracellular Na+ concentration was measured by emission flame photometry. Result\ Amiloride-sensitive Na+ influx decreased linearly as a function of temperatures (about 37℃) in shrunken cells, but increased in acidified cells. The up-regulation of acid-induced Na+/H+ exchange by elevated temperature was enhanced by hypo-osmolarity. Less sensitivity of intracellular H+ site at 41℃ may be the mechanism for the inhibition of shrinkage-induced Na+/H+ exchange by elevated temperature. Heating-mediated explosive increase in the activity of acid-induced Na+/H+ exchange may be due to enhanced extracellular Na+ sensitivity and lower intracellular pH caused by acidic metabolites. Acid-induced Na+/H+ ewxchange contributes to cytoplasmic Na+ accumulation. Conclusion\ These two modes of Na+/H+ exchange with different response to elevated temperature may play different roles in the cellular pathogenesis of heatstroke.
文摘Background Control of hypersecretion of certain hormones is one of the key targets in the treatment of pituitary adenomas. RNA interference has been shown to inhibit protein expression, and thus it may represent a promising method for the treatment of pituitary adenomas. In the present study, transfection efficiency of small interfering RNA （siRNA） was optimized in human prolactinoma cells. Methods First, a method was optimized to extract highly purified human prolactinoma cells in vitro. The extracted cells were verified to retain the physiological features of prolactin （PRL） secretion. Second, three conditions for siRNA transfection were tested by the evaluation of transfectfon efficiency and cell viability. The proper transfection condition was verified for human prolactinoma cells. Third, the siRNA for prolactin was transfected into the human prolactinoma cells, and the suppression of PRL mRNA was evaluated by quantitative real-time reverse transcription-PCR. Results The siRNA of 100 pmol with Lipofectamine 2000 of 5 μl for 1×10^6 cells was proved preferable, with transfection efficiency being 53.3% and cell viability being 69.7%. In the preliminary experiment the siRNA against PRL decreased the mRNA of PRL by 34.0%. Conclusion It is possible to inhibit hormone hypersecretion by RNA interference, that may eventually enable therapeutic siRNA drugs developed.
