Low-frequency subthreshold sympathetic stimulation augments maximal reflex parasympathetic salivary secretion in cats.
Electrical stimulation of the peripheral cut end of the cervical sympathetic trunk for 3 min at frequencies < 1 Hz with pulses of 2-ms duration at supramaximal intensities did not elicit any salivary secretion, but an increase of stimulus frequency over the range 2-10 Hz produced progressively greater salivary secretion, the maximum volume of salivary secretion being evoked at 10 Hz. Frequency-dependent augmentation of parasympathetic reflex submandibular salivary secretion occurred when the lingual nerve was stimulated during repetitive sympathetic stimulation (at frequencies of 0.1-2 Hz) in our sympathectomized cats. The augmentation was found to be linearly related to sympathetic stimulus frequency (regression line calculated by method of least squares; r = 0.939, P < 0.01). This augmentation was abolished by prior treatment with the beta-adrenoceptor blocking drug propranolol (1 mg/kg, P < 0.01 vs. before propranolol) but not by the alpha-adrenoceptor blocking agent phentolamine (1 mg/kg), indicating that the augmented response was mediated via an activation of beta-adrenoceptors. The reduction of the augmentation caused by propranolol had diminished 1 h after its administration, showing that the effect was reversible.
Izumi
H
H
Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan.
Karita
K
K
D000818:Animals; D002415:Cats; D004056:Differential Threshold; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D008297:Male; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012018:Reflex / Q000502:physiology*; D012463:Saliva / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000502:physiology*
D011433:Propranolol; D010646:Phentolamine