α 1 ‐Adrenoceptor subtypes in the mouse mesenteric artery and abdominal aorta

Subtypes of α 1 ‐adrenoceptor‐mediated contractions to noradrenaline in mouse mesenteric artery and abdominal aorta were examined. In mesenteric artery, BMY7378, 5‐methylurapidil, WB4101 and prazosin were inhibited contraction to noradrenaline The good correlation for pA 2 values of antagonists in native α 1D ‐ (rat thoracic aorta) adrenoceptor subtype and pK i values in rat cloned α 1d ‐adrenoceptor with the pA 2 values estimated in the mouse mesenteric artery was obtained. However, the pA 2 value for BMY7378 is significantly lower than the accepted value against the α 1D ‐adrenoceptor subtype. In the abdominal aorta, it was obtained the regional difference for the sensitivity for noradrenaline. In the upper abdominal aorta, the good correlation for the pA 2 values of the antagonists in the native α 1D ‐adrenoceptor subtype and pK i values in the cloned α 1d ‐adrenoceptor with the pA 2 values estimated in the upper abdominal aorta was obtained, and regression line was close to the line of identity. In the lower abdominal aorta, the good correlation for the reported pK i values in the cloned α 1a ‐adrenoceptor subtype with the pA 2 values estimated in the mouse lower abdominal aorta was obtained, and regression line was close to the line of identity. In conclusion, the present functional data in the mouse suggest that (1) α 1D ‐like adrenoceptors are present in the mesenteric artery, (2) there is the regional difference for the sensitivity for noradrenaline in the abdominal aorta and (3) noradrenaline evokes the contraction mediated through α 1D ‐adrenoceptor in the upper abdominal aorta, whereas there is α 1A ‐adrenoceptor‐mediated contraction in the lower abdominal aorta.British Journal of Pharmacology (2001) 134 , 1045–1054; doi: 10.1038/sj.bjp.0704350