碘杂环化合物对离体豚鼠心乳头肌动作电位和收缩力的作用

采用细胞内微电极记录技术,同步观察了3,6-[二甲氨基]-二苯并碘因甲酸盐(IHC-64)对豚鼠心乳头肌细胞动作电位和收缩力的作用。50μmol/L IHC-64抑制心肌收缩力,而不影响快反应动作电位。增加IHC-64浓度,动作电位0相最大峰值(APA)、除极速率(dp/dt_(max))和复极50％和90％时程(APD_(50)、APD_(90))被明显抑制。IHC-64抑制慢反应动作电位,提高细胞外钙浓度可拮抗这种抑制。结果提示,IHC-64主要抑制慢Ca~(2+)内流,同时也部分抑制快Na~+内流,它可能是一种新型B类钙通道阻滞剂。     

31P NMR spectroscopic study of bioenergetic changes in radiation-induced fibrosarcoma-1 after radiation therapy

The effects of localized gamma-irradiation on the in vivo 31P NMR spectra of RIF-1 tumors grown subcutaneously in C3H/HeN mice have been examined before and during the week after treatment. Increases in the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) and in tumor pH, and decreases in the ratio of Pi to the beta phosphorus resonance of the nucleotide triphosphates (beta NTP) were observed in irradiated tumors. The time course of changes in the 31P spectrum following treatment was the opposite of the pattern during untreated growth, and the magnitude and duration of the changes increased with increasing radiation dose, decreasing clonogenic cell survival and increasing growth delay. To examine the possibility that nontherapeutic systemic effects of the tumor irradiation were responsible for the changes observed, a number of animals bearing two tumors were examined. One tumor on each mouse was selectively irradiated. Changes in tumor volume, Pi/beta NTP, PCr/Pi, the ratio of phosphomonoesters to beta NTP, and tumor pH were all significantly different in the treated compared to the untreated tumor on each animal, indicating that these changes in 31P NMR spectra were a response to radiation therapy and not a systemic response to radiation toxicity.