Amylase secretion in response to activation of different autonomic receptors in the rabbit parotid gland

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Abstract
The contribution by different autonomic receptors to the amylase secretion from the parotid gland of the anesthetized rabbit was studied as the response to various parasympathomimetic and sympathomimetic drugs. Amylase secretion by infusions of pilocarpine or parasympathetic nerve stimulation was low, but regularly higher in response to pilocarpine than to parasympathetic nerve stimulation. These effects were reduced to the same level by .beta.-adrenoceptor block, indicating the presence and, also for pilocarpine, the release of catecholamines, probably from the adrenals. Isoprenaline injections produced a high amylase secretion that was blocked by atenolol, indicating that predominantly .beta.1-adrenoceptors were activated. Phenylephrine was without amylase secretory effects. By accepting isoprenaline maximum as maximum for sympathetically produced amylase secretion, a theoretical frequency-response relationship for amylase secretion by sympathetic nerve stimulation could be calculated; ED50 was 0.9 Hz. Under experimental conditions in vivo, there are certain differences between the rat and the rabbit parotid glands in the autonomic control, not only of fluid but particularly of amylase secretion.