HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text All Versions of this Article: 546/3/837    most recent 2002.029686v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lung, M. A. Search for Related Content PubMed PubMed Citation Articles by Lung, M. A.

Autonomic nervous control of myoepithelial cells and secretion in submandibular gland of anaesthetized dogs

Mary A. Lung

In dog submandibular gland, the activity of myoepithelial cells was assessed by simultaneous measurement of intraductal pressure (P_du) and subcapsular pressure (P_ca) using catheter-tip pressure transducers; their resting values were 2.5 ± 0.21 and 3.0 ± 0.19 mmHg, respectively (n = 40). Retrograde infusion of saliva (collected from preceding parasympathetic nerve stimulation) increased P_du (coefficient of 50 mmHg ml^-1 for rates < 1 ml min^-1 and 85 mmHg ml^-1 for higher rates) and P_ca (coefficient of 0.47 mmHg ml^-1 for all rates). Blood flow changes did not affect P_du but increased P_ca (coefficient of 0.04 mmHg ml^-1). Parasympathetic nerve stimulation increased P_du but decreased P_ca abruptly; the response threshold was 0.1 Hz, with maximal responses at 16 Hz. The coefficients for P_du and P_ca on salivary secretion to parasympathetic nerve stimulation in glands with spontaneous blood flow (5.3 10^-3 and 4.87 10^-2 ml min^-1 g^-1 mmHg^-1) were close to their values in glands with constant-flow vascular perfusion (4.9 10^-3 and 3.68 10^-2 ml min^-1 g^-1 mmHg^-1). The finding that P_ca fell despite concomitant increased blood flow suggests contraction of myoepithelial cells. Additional ductal occlusion further increased P_du and enhanced the fall in P_ca, suggesting that the myoepithelial cells can contract when distended. Atropine blocked salivary secretion and responses of P_du and P_ca to parasympathetic nerve stimulation. ACh elicited responses similar to that of parasympathetic nerve stimulation. VIP caused very scanty salivary secretion and gradual slight increases in P_du and P_ca; the change in P_ca was abolished in glands with constant-flow vascular perfusion. Hence, contraction of myoepithelial cells to parasympathetic nerve stimulation is via muscarinic receptors. Sympathetic nerve stimulation increased P_du and decreased P_ca abruptly; the response threshold was 0.1 Hz, with maximal responses at 16 Hz. The coefficients for P_du and P_ca on salivary secretion to sympathetic nerve stimulation in glands with spontaneous blood flow (3.0 10^-3 and 3.2 10^-3 ml min^-1 g^-1 mmHg^-1) were similar to their values in glands with constant-flow vascular perfusion (3.2 10^-3 and 3.1 10^-3 ml min^-1 g^-1 mmHg^-1). The finding that P_ca fell even in glands with constant-flow vascular perfusion suggests contraction of myoepithelial cells. Superimposed sympathetic nerve stimulation immediately enhanced the pressure changes and secretory response to parasympathetic nerve stimulation, indicating that the two autonomic nerves act synergistically to evoke myoepithelial cell contraction. Phentolamine and prazosin but not propranolol and yohimbine blocked the sympathetic enhancement. The finding that phenylephrine, but not clonidine and isoproterenol, abruptly decreased P_ca in glands with constant-flow vascular perfusion suggests that the sympathetic activation of myoepithelial cells is via the ₁-adrenoceptors.

This article has been cited by other articles:

				J. P. Prestifilippo, J. Fernandez-Solari, C. de la Cal, M. Iribarne, A. M. Suburo, V. Rettori, S. M. McCann, and J. C. Elverdin Inhibition of Salivary Secretion by Activation of Cannabinoid Receptors Experimental Biology and Medicine, September 1, 2006; 231(8): 1421 - 1429. [Abstract] [Full Text] [PDF]

				E. Berggreen and H. Wiig Lowering of interstitial fluid pressure in rat submandibular gland: a novel mechanism in saliva secretion Am J Physiol Heart Circ Physiol, April 1, 2006; 290(4): H1460 - H1468. [Abstract] [Full Text] [PDF]