Table 2.

Summary of induced effects on Tethya wilhelmaOverview regarding induced contraction, endogenous contraction rhythm alteration and/or amplitude attenuation by substances used in the present and previous study, including effects on sponges, reported by other authors before.

Substance	Contraction induced	Rhythm altered	Amplitude altered	Signalling pathway known to be influenced	Other reports on sponges
Acetycholine	-	slightly slower rhythm	-	ionotrophic or metabotrophic acetylcholine receptor	Increased rhythm and intensity of contraction in Euspongia officinalis [22], no effect in Cliona celata [5]. Acetylcholine esterase activity in Sycon sp. 21, Hippospongia [35] and T. wilhelma [26]
Nicotine	-	-	-	agonist at ionotrophic acetylcholine receptor	Loss of current at high (cytotoxic) concentrations in Cliona celata [5]
Caffeine	Xa	faster rhythm	attenuated	antagonist at metabotrphic adenosine receptors	-
GABAb	X	n.d.	-	ionotrophic or metabotrophic GABA receptors	No effect in Cliona celata [5]. GABA/mgluR-like receptor gene in Geodia cydonium [19]. High specificity in inducing contractions in T. wilhelma (Ellwanger et al., submitted).
Glutamateb	X	n.d.	-	metabotrophic glutamate receptors	Induces intracellular Ca2+ increase. GABA/mGluR-like receptor gene in Geodia cydonium [19]. Lower specificity than GABA in inducing contractions in T. wilhelma [31]
Glycin	X	faster rhythm	attenuated	metabotrophic glycin receptors	-
Adrenaline	-	very slow, irregular rhythm	-	metabotrophic adrenergic receptor family	Slight current reduction in Cliona celata [5]. Histochemical detection in Sycon sp. [21]; increased rhythm and intensity of contraction in Euspongia officinalis [22]
Serotonine	X	-	-	ionotrophic or metabotrophic serotonine receptors	No effect in Cliona celata [5]. Histochemical detection in Sycon sp. [21], and Tedania ignis [42]
(by NOC-12)c	X	very slow, irregular rhythm	attenuated	intracellular soluble guanylate cyclase	NOS activity in heat stress response of Axinella polypoides and Petrosia ficiformis [48]
cAMPd	X	tendency for slower, irregular rhythm	-	metabotrophic cAMP receptor	Reduced locomotion an altered shape in dissociated Clathrina cerebrum cells [51]; Release of Spongilla lacustris gemmules from dormancy [50]

^a delayed contraction

^b detailed data and results presented elswhere [31]

^c extracellular application, membrane permeable

^d extracellular application, membrane impermeable