HORMONE SUBSTANCES 115 



consistent, and it is quite possible that the changes in ciliary 

 activity caused by ACh may be but secondary results of the 

 action of ACh on some other parts of the ciliated cells, or even 

 on other cells of the organism. 



Rather less work has been done on the effects of adrenaline on 

 ciliary activity, but the results obtained show good agreement. 

 The activity of the ciliated epitheHum of the frog pharynx was 

 found to be increased by 20 to 25 per cent in adrenaline (10~^ 

 g/ml) by Plattner and Hou (1931), and adrenahne also increased 

 the activity of cilia of the mucous membrane of the rabbit trachea 

 (Kordik, Biilbring and Burn, 1952). Invertebrate tissues show 

 similar results, e.g. adrenaline concentrations of 10~^ and 10~^ 

 g/ml were found to accelerate the activity of cilia on the tentacles 

 of Metridium (ten Cate, Coomans and Walop, 1955). Both the 

 rate of ciliary beat (max. of 24 per cent at 10~^ g/ml) and the rate 

 of particle transport (max. 138 per cent at 10~^ g/ml) by the cilia 

 of Mytilus gills were increased by adrenaline at all the concentra- 

 tions used by Biilbring, Burn and Shelley (1953). In protozoa, 

 Bayer and Wense (1936b) extracted a substance from Paramecium 

 which they believed to be adrenaline and which had an adrenaline - 

 like action on the contraction of rabbit intestine. 



Adrenaline consistently accelerates ciliary activity in all the 

 metazoan tissues mentioned above at all of the concentrations 

 used; this shows an important difference from ACh which 

 accelerates ciliary activity at low concentrations and depresses it 

 at higher concentrations. In the presence of adrenaline at 

 concentrations as small as 10~® to 10~^ g/ml, both the frequency 

 of beat and the metachronal wave velocity of Stentor membranelles 

 were increased, particularly the wave velocity, which was increased 

 by about 27 per cent in one experiment at 7 x 10~^ g/ml (Sleigh, 

 1956b). It appears therefore as if the adrenaline acts on apart of the 

 system common to both the contraction and conduction activities. 

 This shows a parallel with heart muscle, where both the rate of 

 beat and the rate of conduction may be increased by adrenaline 

 (Clark, 1927; Prosser, 1950). Perhaps the finding of Goffart and 

 Brown (1947) that the action of adrenaline on striated muscle is 

 closely connected with the potassium concentrations on either side 

 of the muscle membrane may be found to be important for cilia also. 



Noradrenaline had no effect on the ciliary activity of the rabbit 



