DIRECT OBSERVATION OF MICROCIRCULATION OF THE BASAL REGION OF RAT GASTRIC-MUCOSA

We modified and improved techniques for the intravital microscopic obs ervation of the rat gastric microcirculation. The stomach of anestheti zed rats was cut along the greater curvature, and the posterior wall o f the glandular stomach was fixed in a chamber with the serosal side u p and perfused with warmed Tyrode's solution. A portion of the muscula ris externa was resected with the serosa to make an observation window . Vascular casts were studied histologically after the injection of Mo nastral blue B gelatin solution. Vascular casts revealed that most of the microvasculature observed in the window was not located in the sub mucosa, but in the basal part of the mucosa. Microscopic observation s howed that the basal mucosal arterioles branched to form the mucosal c apillaries, and the collecting venules from the mucosal surface were s een in cross-sections to drain into the venules located in the basal m ucosa, without penetrating the muscularis mucosae. Topical application of acetylcholine (0.03-10 mu M) to the window dilated the arterioles, and topical application of epinephrine (0.03-3 mu M) constricted them dose-dependently without affecting the collecting venules and the ven ules. This method made possible the direct observation of the microvas culature in the basal mucosa of the stomach, in which common microvess el characteristics were shown.