Effects of methacholine and uridine 5'-triphosphate on tracheal mucus rheology in mice.
We compared the action of methacholine (MCh) and uridine 5'-triphosphate (UTP) with and without pretreatment with the chloride channel blocker 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS) on the transepithelial potential difference (PD), the mucus collection rate (MCR), and tracheal mucus rheology using anesthetized C57BL/6 mice. The cystic fibrosis transmembrane conductance regulator (CFTR) blocker 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB) was also used as a pretreatment for MCh. After collecting baseline mucus for 1.5 h, mucus secretion was stimulated by instilling 5 microl of 10(-2) M MCh or UTP around the upper trachea. There was a significant increase in PD after MCh or UTP stimulation (-21.3+/-2.0 mV MCh versus -14.1+/-1.6 mV control; -25.4+/-2.5 mV UTP versus -19.2+/-1.9 mV control). When UTP administration was preceded by DIDS, PD shifted from -15.2+/-2.9 to -12.0+/-2.2 mV. When MCh was preceded by DIDS or by NPPB, there was no change in PD. There was a significant decrease in mucus rigidity index, logG*, with MCh (2.54+/-0.09 versus 2.99+/-0.14 for control), similar to that previously reported in other species. With UTP, 14 of 16 mice responded in terms of PD becoming more negative, and of these, there was a significant difference in logG* after UTP administration (2.29 +/-0.10 versus 2.57+/-0.10 for control), whereas there was no change in logG* with DIDS administration before UTP. When DIDS administration preceded MCh, there was a diminished but still significant decrease in logG* from control, whereas there was no change in logG* when NPPB was preadministered. The control mucus collection rate was 0.19+/-0.09 mg/h, whereas after MCh stimulation, it increased to 2.83+/-0.78 mg/h. No significant difference was measured in the MCR after either UTP or DIDS+UTP stimulation. DIDS+MCh and NPPB+MCh both resulted in significant increases in MCR, but of a much smaller magnitude than that for MCh alone. We conclude that hypersecretion owing to UTP in C57BL/6 mice is less vigorous than with MCh, reflecting the limited population of Ca(2+)-dependent Cl(-) channels stimulated by UTP P(2) receptors. The action of MCh on tracheal mucus secretion in mice appears to involve both CFTR- and non-CFTR-dependent chloride channels.
Sudo
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Pulmonary Research Group, University of Alberta, Edmonton, Canada.
Lee
M M
MM
Boyd
W A
WA
King
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004548:Elasticity; D004594:Electrophysiology; D004847:Epithelial Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D016210:Methacholine Chloride / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008839:Microelectrodes; D009093:Mucus / Q000378:metabolism*; D012212:Rheology; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism; D014544:Uridine Triphosphate / Q000494:pharmacology*
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D014544:Uridine Triphosphate