Mupanomunda M M, Ishioka N, Bukoski R D
Section of Hypertension and Vascular Research, University of Texas Medical Branch, Galveston, Texas 77555-1065, USA.
Am J Physiol. 1999 Mar;276(3):H1035-42. doi: 10.1152/ajpheart.1999.276.3.H1035.
We recently described a perivascular sensory nerve-linked dilator system that can be activated by interstitial Ca2+ (Ca2+isf). The present study tested the hypothesis that Ca2+isf in the rat duodenal submucosa varies through a range that is sufficient to activate this pathway. An in situ microdialysis method was used to estimate Ca2+isf. When the duodenal lumen was perfused with Ca2+-free buffer, Ca2+isf was 1.0 +/- 0.13 mmol/l. Ca2+isf increased to 1.52 +/- 0.04, 1.78 +/- 0.10, and 1.89 +/- 0.1 when the lumen was perfused with buffer containing 3, 6, and 10 mmol/l Ca2+, respectively (P < 0.05). Ca2+isf was 1.1 +/- 0.06 mmol/l in fasted animals and increased to 1. 4 +/- 0.06 mmol/l in free-feeding rats (P < 0.05). Wire myography was used to study isometric tension responses of isolated mesenteric resistance arteries. Cumulative addition of extracellular Ca2+-relaxed serotonin- and methoxamine-precontracted arteries with half-maximal effective doses of 1.54 +/- 0.05 and 1.67 +/- 0.08 mmol/l, respectively (n = 5). These data show that duodenal Ca2+isf undergoes dynamic changes over a range that activates the sensory nerve-linked dilator system and indicate that this system can link changes in local Ca2+ transport with alterations in regional resistance and organ blood flow.
我们最近描述了一种可被细胞间钙离子（Ca2+isf）激活的血管周围感觉神经连接的扩张系统。本研究检验了这样一个假说：大鼠十二指肠黏膜下层的Ca2+isf在足以激活该通路的范围内变化。采用原位微透析法估算Ca2+isf。当用无钙缓冲液灌注十二指肠腔时，Ca2+isf为1.0±0.13 mmol/L。当分别用含3、6和10 mmol/L Ca2+的缓冲液灌注肠腔时，Ca2+isf分别升至1.52±0.04、1.78±0.10和1.89±0.1（P<0.05）。禁食动物的Ca2+isf为1.1±0.06 mmol/L，自由进食大鼠的Ca2+isf升至1.4±0.06 mmol/L（P<0.05）。采用线肌张力测定法研究离体肠系膜阻力动脉的等长张力反应。细胞外Ca2+的累积添加使血清素和甲氧明预收缩的动脉舒张，半数有效剂量分别为1.54±0.05和1.67±0.08 mmol/L（n = 5）。这些数据表明，十二指肠Ca2+isf在激活感觉神经连接的扩张系统的范围内发生动态变化，并表明该系统可将局部Ca2+转运的变化与区域阻力和器官血流的改变联系起来。
