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Because the discoordination between swallowing and respiration may cause severe respiratory disorders such as aspiration pneumonia, understanding the neuronal mechanisms underlying such coordination is important. Recently, it was reported that medullary noradrenergic neurons are involved in evoking esophageal-gastric relaxation reflex, leading to a hypothesis that such neurons are also involved in swallowing-respiration coordination. We tested this hypothesis using an in vitro brain-stem preparation obtained from neonatal rats. A temporal inhibition of respiratory rhythm was consistently observed when swallowing activity was induced by electrical stimulations to the supralaryngeal nerve. We found that a broad adrenergic receptor agonist, norepinephrine, markedly blocked the swallowing-induced temporal inhibition of respiration. Further studies revealed that swallowing-induced respiratory inhibition is blocked by an alpha2-adrenergic receptor agonist and enhanced by an alpha2-adrenergic receptor antagonist, indicating an important role of alpha2-adrenergic receptors in regulation of the coordination between swallowing and respiration in vitro. [ABSTRACT FROM AUTHOR]

We examined the secretory effects of two β2-adrenergic agonists, procaterole and terbutaline, on the submandibular glands of anesthetized rats. After stimulation with these agents with and without a range of antagonists (non-specific α and β-adrenergic blockers), submandibular saliva was collected. The flow rate, protein concentration, the electrophoretic patterns, and amino acid composition of saliva were examined. These parameters were compared with their counterparts in saliva stimulated with isoproterenol (IPR), with and without antagonists. Assessed by these criteria, secreted proteins were classified as the α- or β-type. In addition, IPR-stimulated proteins were compared in submandibular saliva of rats chronically treated with IPR or procaterole. Both β2-agonists were potent secretagogues for the submandibular glands of rats. All α-antagonists completely abolished the secretory effects elicited by both β2-agonists, with the exceptions of carteolol and propranolol. However, no blocking agent abolished the secretory effects of IPR (60 mg/kg). The types of proteins in all submandibular saliva samples elicited by both β2-agonists with and without antagonists were the β-type. Enlargement of the submandibular glands was not observed in rats subjected to chronic administration of procaterole, nor were abnormal and additional proteins observed, as confirmed by electrophoresis and by the amino acid analyses. [ABSTRACT FROM AUTHOR]

The submandibular glands of rats subjected to application of an incisal bite plane became slightly, but not significantly, enlarged. However, in comparison with control animals, they secreted additional proteins identical with those secreted by glands enlarged by periodic incisor amputation or chronic isoproterenol treatment. [ABSTRACT FROM AUTHOR]

Application of an incisal bite plane for as little as three d caused a significant increase in the size of the sublingual glands of rats, with some evidence of hyperplasia and hypertrophy of the acinar cells. The enlargement had few effects on salivary secretion, and the gland changes were reversible. [ABSTRACT FROM AUTHOR]

The sublingual glands of adult, male rats secreted considerable volumes of saliva in response to several cholinergic agonists, but very little in response to α-adrenergic stimuli and none in response to a β-adrenergic agonist. The types of proteins secreted were quite different from those in submandibular and parotid saliva or serum, and were largely independent of the nature of the stimulus. However, some differences in staining intensity of electrophoretic patterns occurred both between stimuli and with the same stimulus used on different rats. [ABSTRACT FROM AUTHOR]

The types of proteins secreted by rat submandibular glands in response to secretory stimulation with epinephrine, norepinephrine, or phenyl-ephrine were dose-dependent. At relatively high doses the proteins secreted were characteristic of α-adrenergic stimulation, whereas at low doses they were characteristic of β-adrenergic stimulation. [ABSTRACT FROM AUTHOR]

We examined the secretory effects of two beta 2-adrenergic agonists, procaterole and terbutaline, on the submandibular glands of anesthetized rats. After stimulation with these agents with and without a range of antagonists (non-specific alpha- and beta-adrenergic blockers), submandibular saliva was collected. The flow rate, protein concentration, the electrophoretic patterns, and amino acid composition of saliva were examined. These parameters were compared with their counterparts in saliva stimulated with isoproterenol (IPR), with and without antagonists. Assessed by these criteria, secreted proteins were classified as the alpha- or beta-type. In addition, IPR-stimulated proteins were compared in submandibular saliva of rats chronically treated with IPR or procaterole. Both beta 2-agonists were potent secretagogues for the submandibular glands of rats. All beta-antagonists completely abolished the secretory effects elicited by both beta 2-agonists, with the exceptions of carteolol and propranolol. However, no blocking agent abolished the secretory effects of IPR (60 mg/kg). The types of proteins in all submandibular saliva samples elicited by both beta 2-agonists with and without antagonists were the beta-type. Enlargement of the submandibular glands was not observed in rats subjected to chronic administration of procaterole, nor were abnormal and additional proteins observed, as confirmed by electrophoresis and by the amino acid analyses.