Matsumoto H, Baron C B, Coburn R F
Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia.
J Pharmacol Exp Ther. 1994 Aug;270(2):708-12.
Five-minute exposures of aortic smooth muscle to 15 microM norepinephrine (NOR) under normoxia resulted in significant increases in inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] (152%), inositol 1,4-bisphosphate [Ins(1,4)P2] (171%) and inositol 4-phosphate [Ins(4)P] (203%) contents compared with values measured in unstimulated muscle but no changes in inositol 1,3,4-trisphosphate [Ins(1,3,4)P3], inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] inositol 1/3-phosphate [Ins(1/3)P] or inositol 1,3/3,4-bisphosphate [Ins(1,3/3,4)P2] contents. Increases in Ins (1,4,5)P3 content and the contents of its by-products persisted or increased for at least 20 min of NOR exposure during normoxia. After a rapid decrease in Po2 at 5 min of NOR exposure, there were parallel decreases in Ins(1,4,5)P3 and Ins(1,4)P2 contents and in force. Ins(1,4,5)P3 and Ins(1,4)P2 contents were significantly decreased to 85 +/- 4.3% and 70 +/- 9.4% of control, respectively, at a time just after onset of relaxation. At near-maximal relaxation, Ins(1,4,5)P3 and Ins(1,4)P2 contents were decreased to 36.5 +/- 5.8% and 59.2 +/- 16.8%, respectively, of control normoxia values (P < .05). After readmission of O2 to the bubbling gas, Ins(1,4,5)P3 and Ins(1,4)P2 contents rapidly increased. Comparing decreased PO2-evoked [PCr] and [ATP] (phosphocreatine and adenosine triphosphate) decrements (measured previously; Coburn et al., 1992) with our present data, threshold [PCr] and [ATP] for a decrease in Ins(1,4,5)P3 content were shown to be 0.5 and 0.8 mM, respectively, and [PCr] and [ATP] at the time of 50% decrease in Ins(1,4,5)P3 content were 0.3 and 0.7 mM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
在常氧条件下，将主动脉平滑肌暴露于15微摩尔去甲肾上腺素（NOR）5分钟，与未刺激的肌肉相比，肌醇1,4,5-三磷酸[Ins(1,4,5)P3]含量显著增加（152%），肌醇1,4-二磷酸[Ins(1,4)P2]含量增加（171%），肌醇4-磷酸[Ins(4)P]含量增加（203%），但肌醇1,3,4-三磷酸[Ins(1,3,4)P3]、肌醇1,3,4,5-四磷酸[Ins(1,3,4,5)P4]、肌醇1/3-磷酸[Ins(1/3)P]或肌醇1,3/3,4-二磷酸[Ins(1,3/3,4)P2]含量无变化。在常氧条件下，NOR暴露至少20分钟期间，Ins(1,4,5)P3含量及其副产物含量持续增加或升高。NOR暴露5分钟后Po2迅速下降，Ins(1,4,5)P3和Ins(1,4)P2含量以及张力随之平行下降。在刚开始松弛时，Ins(1,4,5)P3和Ins(1,4)P2含量分别显著降至对照值的85±4.3%和70±9.4%。在接近最大松弛时，Ins(1,4,5)P3和Ins(1,4)P2含量分别降至对照常氧值的36.5±5.8%和59.2±16.8%（P<0.05）。向鼓泡气体中重新通入O2后，Ins(1,4,5)P3和Ins(1,4)P2含量迅速增加。将先前测量的PO2降低引起的磷酸肌酸[PCr]和三磷酸腺苷[ATP]减少量（Coburn等人，1992年）与我们目前的数据进行比较，发现Ins(1,4,5)P3含量降低的阈值[PCr]和[ATP]分别为0.5和0.8毫摩尔，Ins(1,4,5)P3含量降低50%时的[PCr]和[ATP]分别为0.3和0.7毫摩尔。（摘要截短至250字）
