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PubMed1983

Some aspects of the regulation of ciliary activity in mammalian somatic cells.

Ciliated cortices isolated from rabbit trachea or oviduct can be reactivated with MgATP (2.4 mM, approx). We analyzed the effects of varying concentrations (0.1-100 mM) of Ca2+ and Mn2+ on the number of cortices which reactivated, as a percentage of the controls. Although reactivation can be inhibited at approximately 10(-2) M cation, we believe that this inhibition might be the result of decreasing MgATP due to competition by Ca2+ and Mn2+ for ATP cation binding sites, rather than cation interactions with the axoneme proper. In addition, whole isolated ciliated cells were obtained from trachea or oviduct by a simple, one step pronase digestion. These cells were incubated with the calcium ionophore A23187 in the presence of 2 mM Ca2+. Inhibition of ciliary activity in 50% of the cells did not occur until about 60 min of incubation. It is believed that what we have observed is cell toxicity rather than a direct effect on the cilia.

Adenosine Triphosphate↗

PubMed1981

Microtubule sliding in cilia of the rabbit trachea and oviduct.

Evidence for active sliding of microtubules during ciliary activity has been demonstrated in a number of organisms: sea urchin sperm flagella, protozoan cilia, and mollusc gill cilia. Although there is evidence that active sliding also occurs in mammalian sperm flagella, there is little or no information on whether active sliding of microtubules also occurs in the short (5-micron) cilia of the mammalian trachea or oviduct. Since these cilia are important in tracheobronchial clearance and ovum transport, respectively, it has been important to demonstrate that microtubule sliding is also involved in the activity of somatic cilia. Ciliated apical portions (cortices) and cilia were isolated from rabbit trachea and oviduct, using Triton X-100 to demembranate the cilia. Most of the ciliated cortices reactivated upon addition of ATP, whereas isolated cilia reactivated to a lesser extent. When preparations of cilia were digested with trypsin before or after ATP addition, disintegration of axonemal doublets occurred with about the same frequency as reactivation. These events were recorded using Nomarski optics and dark-field microscopy. When isolated cilia which had been digested by trypsin and exposed to ATP were also prepared for electron microscopy by negative staining, telescoping of doublet microtubules from axonemes could be shown. These results demonstrate that mammalian somatic ciliary doublet microtubules actively slide in a manner similar to that described for invertebrate cilia.

Adenosine Triphosphate↗