Preponderance of beta adrenergic receptors in the gastric fundus of the rat.

There are two kinds of adrenergic receptors in rat fundus (stomach), the alpha receptors are stimulated with adrenaline and noradrenaline and can be blocked effectively with azapetine and the beta receptors are stimulated with isoprenaline and adrenaline and can be blocked effectively with propranolol. Adrenaline, noradrenaline and isoprenaline all produce inhibition of acetylcholine induced contractions in both untreated and reserpinized tissues that can be antagonized with azapetine and propranolol on its specific receptors but propranolol has a greater capacity to decrease the sensitivity of both untreated and reserpinized tissues to isoprenaline and adrenaline than azapetine can in case of noradrenaline and adrenaline.