Adrenaline released from adrenal medullary chromaffin (AMC) cells in mammals plays a critical role for fight or flight responses in emergency. Adrenaline secretion by AMC cells is mainly induced by neuronal input from the sympathetic nerve. Acetylcholine (ACh) mediates the neuronal transmission to AMC cells through nicotinic and/or muscarinic receptors. Because muscarinic signal is transmitted in a G protein-dependent manner, it is thought to be relatively slow, compared with the transmission by ionotropic nicotinic receptors. In this review, I first discuss the muscarinic receptor-mediated catecholamine secretion from the phylogenetic point of view. Next, I elucidate the signal transduction mechanisms for the muscarinic secretion in mammalian AMC cells. Then, the physiological functions of adrenaline in the lung, the skeletal muscle, and the immune system are discussed. Finally, I explore muscarinic receptor-mediated excessive secretion of adrenaline from AMC cells in the spontaneously hypertensive rat (SHR), a model animal for hypertension. This review aims to facilitate our understanding of why the organism develops the adrenal medullary system with adrenaline as a humoral factor in addition to the sympathetic nervous system, and of how the adrenal medullary system functions as a feedforward regulator for fight or flight responses.