Pouch dilatation

Fig. 13.12. Diagram showing the appearance of pouch dilatation due to slippage of the gastric band...

Hypoxia also causes the release of adenosine from cardiac myocytes. Adenosine in a potent dilator of coronary arteries. It has been shown that adenosine activates K xp currents in single coronary artery smooth muscle cells (Dart and Standen, 1993, 1994). Activation of the K xp channel is also involved in the hypoxic vasodilation in the cerebral, renal (Loutzen-hiser and Parker, 1994), skeletal muscle, and cremaster muscle and cheek pouch circulations (see Nelson and Quayle, 1995). Activation of K xp channels in these vascular beds may be a direct consequence of hypoxia on a smooth muscle oxygen sensor, an effect of hypoxia on smooth muscle cell metabolism, or through the release of vasodilator metabolites like adenosine from surrounding tissue, similar to hypoxic coronary vasodilation. 

PGIj reduces peripheral vascular resistance in humans [156] and in animals [240]. In the rat cremaster muscle [255] and in the hamster cheek pouch [256] preparations, PGI2 causes a dose-dependent dilatation of arterioles whereas the postcapillary venules remain insensitive to PGI2 [255]. The results of these simple experiments fit... 

Another interesting approach is Gelfoam , which is made of absorbable gelatin sponge USP. It can be inserted in the conjimctival pouch in the form of small disks (e.g 4 mm in diameter and 0.5 mm thick) impregnated with drag solutions. They have been shown to improve the managanent of pupillary dilation in humans as well as the delivery of pilocarpine [104-106]. 

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