Role of calcium and calmodulin in ciliary stimulation induced by acetylcholine

Abstract

The goal of this work was to elucidate the molecular events underlying stimulation of ciliary beat frequency (CBF) induced by acetylcholine (ACh) in frog esophagus epithelium. ACh induces a profound increase in CBF and in intracellular Ca(2+) concentration ([Ca(2+)](i)) through M(1) and M(3) muscarinic receptors. The [Ca(2+)](i) slowly decays to the basal level, while CBF stabilizes at an elevated level. These results suggest that ACh triggers Ca(2+)-correlated and -uncorrelated modes of ciliary stimulation. ACh response is abolished by the phospholipase C (PLC) inhibitor U-73122 and by depletion of intracellular Ca(2+) stores but is unaffected by reduction of extracellular Ca(2+) concentration and by blockers of Ca(2+) influx. Therefore, ACh activates PLC and mobilizes Ca(2+) solely from intracellular stores. The calmodulin inhibitors W-7 and calmidazolium attenuate the ACh-induced increase in [Ca(2+)](i) but completely abolish the elevation in CBF. Therefore, elevation of [Ca(2+)](i) is necessary for CBF enhancement but does not lead directly to it. The combined effect of Ca(2+) elevation and of additional factors, presumably mobilized by Ca(2+)-calmodulin, results in a robust CBF enhancement.

Nervous control of ciliary beating by Cl-, Ca2+ and calmodulin inTritonia diomedea

“…We place its role downstream of Ca 2+ release from internal stores because W-7 and calmidazolium attenuate the observed caffeine excitation. Calmodulin has been implicated in many of the described CBF control pathways (Stommel and Stephens, 1985;Zagoory et al, 2001;Zagoory et al, 2002). Some researchers attribute W-7 and calmidazolium reduction of CBF excitation to nonspecific chelating effects, instead believing that Ca 2+ directly binds to ciliary beating mechanism (Salathe and Bookman, 1999).…”

“…Ciliary beating may be under hormonal control (Verdugo, 1980;Korngreen and Priel, 1996;Korngreen et al, 1998;Lieb et al, 2002;Barrera et al, 2004) or nervous control via dopamine and neuropeptides (Willows et al, 1997;Woodward and Willows, 2006), serotonin (Goldberg et al, 1994;Christopher et al, 1996;Willows et al, 1997;Nguyen et al, 2001; Doran et al, 2004), acetylcholine (ACh) (Salathe and Bookman, 1999;Zagoory et al, 2001;Zagoory et al, 2002) or depolarization (Aiello and Guideri, 1964;Mackie et al, 1969;Mackie et al, 1976;Murakami and Takahashi, 1975). Work permitting any distinction between these control mechanisms is sparse and this may be due, in part, to technical challenges presented by vertebrate models.…”

“…paramecium (Eckert, 1972), is an increase in internal free Ca 2+ (Verdugo, 1980;Villalon et al, 1989;Salathe and Bookman, 1995;Korngreen and Priel, 1996). Studies of CBF have yielded different possible mechanisms for increasing internal free Ca 2+ , including the phospholipase C (PLC) pathway (Christopher et al, 1999;Zagoory et al, 2001), both protein kinase C (PKC) (Gertsberg et al, 1997;Christopher et al, 1999;Barrera et al, 2004) and protein kinase A (PKA) (Braiman et al, 1998;Zagoory et al, 2002;Lieb et al, 2002), inositol 1,4,5-triphosphate (Barrera et al, 2004), nitrous oxide (Uzlander and Priel, 1999;Runer and Lindberg, 1999;Doran et al, 2003) and cAMP (Stommel and Stephens, 1985;Aiello, 1990). The next step in signal transduction after an increase in internal calcium may be direct binding of Ca 2+ to the dynein motor (Salathe and Bookman, 1999) or Ca 2+ -calmodulin activation of kinases or phosphodiesterases (Zagoory et al, 2001), or possibly both.…”

“…Studies of CBF have yielded different possible mechanisms for increasing internal free Ca 2+ , including the phospholipase C (PLC) pathway (Christopher et al, 1999;Zagoory et al, 2001), both protein kinase C (PKC) (Gertsberg et al, 1997;Christopher et al, 1999;Barrera et al, 2004) and protein kinase A (PKA) (Braiman et al, 1998;Zagoory et al, 2002;Lieb et al, 2002), inositol 1,4,5-triphosphate (Barrera et al, 2004), nitrous oxide (Uzlander and Priel, 1999;Runer and Lindberg, 1999;Doran et al, 2003) and cAMP (Stommel and Stephens, 1985;Aiello, 1990). The next step in signal transduction after an increase in internal calcium may be direct binding of Ca 2+ to the dynein motor (Salathe and Bookman, 1999) or Ca 2+ -calmodulin activation of kinases or phosphodiesterases (Zagoory et al, 2001), or possibly both. Unfortunately, little is known of possible electrical control of these pathways, though most early results were consistent with such a hypothesis (Aiello and Guideri, 1964;Mackie et al, 1969;Mackie et al, 1976;Murakami and Takahashi, 1975;Saimi et al, 1983a;Saimi et al, 1983b).…”

Substance P and acetylcholine are co-localized in the pathway mediating mucociliary activity in Rana pipiens

“…Stimulation of mucociliary systems is regulated via acetylcholine (Aiello et al, 1991,Zagoory et al, 2001, SP (Hernández & Aiello, 1992), Lindberg et al 1986aLindberg et al ,1986b, nitric oxide (Alberty et at., 2004 ) and purinergic compounds (Braiman et al, 2000a,Zagoory et al, 2002. The action of acetylcholine and part of the effect of SP in the mucociliary system in the frog palate were blocked by atropine.…”