Suppression of carbachol-induced oscillatory Cl- secretion by forskolin in rat parotid and submandibular acinar cells.
Sympathetic stimulation induces weak salivation compared with parasympathetic stimulation. To clarify this phenomenon in salivary glands, we investigated cAMP-induced modulation of Ca(2+)-activated Cl(-) secretion from rat parotid and submandibular acinar cells because fluid secretion from salivary glands depends on the Cl(-) secretion. Carbachol (Cch), a Ca(2+)-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 Ca(2+)-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.
Shintani
Takahide
T
Department of Oral Physiology, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima 734-8553, Japan.
Hirono
Chikara
C
Sugita
Makoto
M
Iwasa
Yoshiko
Y
Shiba
Yoshiki
Y
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D017920:Antiporters / Q000378:metabolism; D002217:Carbachol / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D006096:Gramicidin / Q000494:pharmacology; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D017920:Antiporters; D018118:Chloride Channels; D002712:Chlorides; D018721:Muscarinic Agonists; D010726:Phosphodiesterase Inhibitors; D006096:Gramicidin; D005576:Colforsin; D002217:Carbachol; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine