Table 5

 

Effect of vertebrate hormones  (concentration = mg/ml)  on the cAMP level of Tetrahymena

 

(Csaba G., Nagy S.U., Acta biol. med. germ. 35: 1399-1401, 1976)

 

Signal

Concentration

cAMP (pmole/assay)

Significance p<

Control

 

 

18.21±2.95

 

Epinephrine

 

10-8

30.3±4.81

0.05

Insulin

 

10-3

36.25±7.19

0.01

Glucagon

 

10-3

32.11±4.6

0.05

TSH

 

10-3

25.45±5.93

0,3

 

 

 

Conclusions:

 

  1. Sugar metabolism influencing hormones significantly elevate cAMP level of Tetrahymena.
  2. TSH, a nonsense hormone for Tetrahymena, does not influence significantly cAMP level.
  3. The uniformity in influencing cAMP level can explain why insulin and adrenalin effected in the same direction in case of sugar metabolism (Table 4).
  4. Effects through a cAMP mechanism by hormones allow the supposition of the presence of receptors.

 

 

Receptors for insulin  are present in the plasma membrane of Tetrahymena and their binding can be inhibited by insulin pretreatment (Csaba, G., Sudár, F., Nagy, S.U., Dobozy, O. Localization of hormone receptors in Tetrahymena, Protoplasma 91, 179-189, 1977).

 

Binding sites for thyroxine (T4) and triiodothyronine (T3) are also present in the plasma membrane (instead of cytosol) at this low level of evolution (Csaba et al. Protoplasma, 91, 179, 1977 and Csaba, G., Sudár, F., Demonstration of triiodothyronine binding sites of Tetrahymena by a new scanning autoradiography method. Acta Biol. Med. Germ. 37, 1381-1386, 1978).