Table 3

Effect of biogenic amines on the cAMP level of Tetrahymena.

Signal mol.	Concentrat-ion (M)	cAMP pmole ±s.d	Phagocyte coefficient^X	Reference
Control		19 ±2.2	1.00	Csaba, G., Nagy, S.U., Lantos, T. Acta Biol. Med. Germ. 35: 259-261, 1976
Histamine	10^-9	25.7 ±10.9*	1.65 ±0.28
Serotonin	10^-8	25.6 ±10.7^+	1.26 ±0.17
Gramine	10^-8	3.1 ±1.6^+	1.06 ±0.04
5-methoxy-tryptamine	10^-8	2.8 ±1.1^+	1.16 ±0.07
Tryptamine	10^-8	2.5 ±1.2^+	1.11±0.03

Significance: *=p<0.5; ⁺=p<0.01

Phagocyte coefficient: average number of Indian ink containing vacuoles in the treated cells/average number of Indian ink containing vacuoles in the simultaneous control

Conclusions:

1. Tetrahymena contain cAMP.
2. Serotonin and histamine raised cAMP level, however not significantly.
3. Serotonin antagonists significantly reduced cAMP level.