Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Brazil.
Life Sci. 2013 Mar 21;92(10):569-75. doi: 10.1016/j.lfs.2013.01.016. Epub 2013 Jan 24.
We previously reported that mechanical atrial stretch (AS) by balloon distention increased gastric tonus in anesthetized rats. The present study evaluated the effect of AS on the gastric emptying of a liquid test meal in awake rats and its underlying neural mechanisms.
Anesthetized male rats received a balloon catheter into the right atrium and a gastrostomy cannula. The next day, mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), and cardiac output (CO) were continuously monitored. After the first 20min of monitoring (basal interval), the balloon was either distended or not (control) with 30, 50, or 70μl saline for 5min. Fifteen minutes later, the rats received the test meal (glucose solution with phenol red), and fractional gastric dye retention was determined 10, 20, or 30min later.
Heart rate and CVP values were transiently increased by 50 or 70μl AS but not 30μl AS, whereas gastric emptying was slower after 30, 50, or 70μl AS than after sham distention. Subdiaphragmatic vagotomy or splanchnicotomy+celiac ganglionectomy and capsaicin, ondansetron, hexamethonium, L-NAME, and glibenclamide treatment prevented the AS-induced delay in gastric emptying, whereas atropine and guanethidine treatment failed to prevent it.
Atrial stretch inhibited the gastric emptying of liquid via non-adrenergic and non-cholinergic pathways that activate nitric oxide-K(+)ATP channels.
我们之前报道过，通过球囊扩张对心房的机械牵张（AS）可增加麻醉大鼠的胃张力。本研究评估了 AS 对清醒大鼠液体试餐排空的影响及其潜在的神经机制。
麻醉雄性大鼠接受右心房球囊导管和胃造口术套管。次日，连续监测平均动脉压（MAP）、心率（HR）、中心静脉压（CVP）和心输出量（CO）。在监测的前 20min（基础间隔）后，球囊分别用 30、50 或 70μl 生理盐水扩张（AS）或不扩张（对照）5min。15min 后，大鼠给予试餐（含酚红的葡萄糖溶液），10、20 或 30min 后测定胃内染料保留分数。
50 或 70μl AS 可短暂增加 HR 和 CVP 值，但 30μl AS 不会；而 30、50 或 70μl AS 后胃排空较假扩张延迟。膈下迷走神经切断术或内脏神经切断术+腹腔神经节切除术和辣椒素、昂丹司琼、六烃季铵、L-NAME 和格列本脲处理可预防 AS 引起的胃排空延迟，而阿托品和胍乙啶处理不能预防。
心房牵张通过激活一氧化氮-K（+）ATP 通道的非肾上腺素能和非胆碱能途径抑制液体胃排空。
