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This Article Full Text Full Text (PDF) All Versions of this Article: 294/3/G738    most recent 00239.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Shintani, T. Articles by Shiba, Y. PubMed PubMed Citation Articles by Shintani, T. Articles by Shiba, Y.

HORMONES AND SIGNALING

Suppression of carbachol-induced oscillatory Cl^– secretion by forskolin in rat parotid and submandibular acinar cells

Department of Oral Physiology, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima, Japan

Submitted 27 May 2007 ; accepted in final form 8 January 2008

Sympathetic stimulation induces weak salivation compared with parasympathetic stimulation. To clarify this phenomenon in salivary glands, we investigated cAMP-induced modulation of Ca²⁺-activated Cl^– secretion from rat parotid and submandibular acinar cells because fluid secretion from salivary glands depends on the Cl^– secretion. Carbachol (Cch), a Ca²⁺-increasing agent, induced hyperpolarization of the cells with oscillatory depolarization in the current clamp mode of the gramicidin-perforated patch recording. In the voltage clamp mode at –80 mV, Cch induced a bumetanide-sensitive oscillatory inward current, which was larger in rat submandibular acinar cells than in parotid acinar cells. Forskolin and IBMX, cAMP-increasing agents, did not induce any marked current, but they evoked a small nonoscillatory inward current in the presence of Cch and suppressed the Cch-induced oscillatory inward current in all parotid acinar cells and half (56%) of submandibular acinar cells. In the current clamp mode, forskolin + IBMX evoked a small nonoscillatory depolarization in the presence of Cch and reduced the amplitude of Cch-induced oscillatory depolarization in both acinar cells. The oscillatory inward current estimated at the depolarized membrane potential was suppressed by forskolin + IBMX. These results indicate that cAMP suppresses Ca²⁺-activated oscillatory Cl^– secretion of parotid and submandibular acinar cells at –80 mV and possibly at the membrane potential during Cch stimulation. The suppression may result in the weak salivation induced by sympathetic stimulation.

Na⁺-K⁺-2Cl^– cotransporter; Cl^– channel; cAMP; gramicidin-perforated patch recording; bumetanide