In order to investigate the changes of the distribution and morphological feature of substance P receptor(SPR)in medullary
visceral zone(MVZ) after acute myocardioischemia,16 rats were used to experiment with anti SPR,anti Fos or anti Fos/SPR immunohistochemical stain by ABC method,10 of which was given vasoperessin systematically until myocardioischemia appeared on ECG.The results showed that Fos
positive neurons appeared in MVZ,and SPR positive structures were also densely situated in MVZ.The morphological feature of them differed according to whether
vasopressin was introveinously injected.In no vasopressin group,SPR immunoreaction was weak in decussation of pyramid(PYX)and area postrema(AP) level;whereas,it became strong in vasopressin group.In addition,SPR positive fibers in dorsal motor nucleus of vagus(nmdX)were thick and curved(wool shaped)in normal.But they became thin and smooth after vasopressin was given.Furthermore,30% of SPR positive neurons were also Fos immunoreactive,suggesting that part of SPR LI neurons were involved in conduction and modulation of myocardial ischemica stress induced by vasopressin.