Neuronal control of the cardiac responses to osmotic stress in the gastropod limpet Patella caerulea.
Mediterranean limpets Patella caerulea were exposed to different salinity conditions and treated with drugs interfering with neuronal control of heartbeat. Heart rate was monitored using a non-invasive method. Limpets were superfused with control (33 g l(-1)), hyposaline (0 and 10 g l(-1)) or hypersaline (56 and 66 g l(-1)) artificial seawater. Under osmotic stress the limpets showed an initial increase of heart rate, followed by acardia, particularly under hyposalinity. The tachycardia observed after exposure to 56 g l(-1) was abolished in the animals injected with a selective sodium channel blocker, tetrodotoxin (TTX), or with a serotoninergic antagonist, methysergide. Injection of TTX also partly prevented the acardia occurring at 0 g l(-1). The acardia was completely prevented after injection with atropine and benzoquinonium, two selective cholinergic antagonists. These findings indicate that cardiac responses of P. caerulea to variations in external salinity are regulated by an extrinsic neuronal control involving the serotoninergic and the cholinergic systems in the tachycardic and acardic responses, respectively.
Bini
Giada
G
Department of Animal Biology and Genetics, University of Florence, 50125 Florence, Italy. giada.bini@unifi.it
Pugliese
Anna Maria
AM
Pepeu
Giancarlo
G
Chelazzi
Guido
G
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D049851:Gastropoda / Q000187:drug effects* / Q000502:physiology*; D006321:Heart / Q000187:drug effects / Q000294:innervation* / Q000502:physiology*; D008784:Methysergide / Q000494:pharmacology; D009997:Osmotic Pressure / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012965:Sodium Chloride / Q000032:analysis / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014867:Water / Q000737:chemistry
D000644:Quaternary Ammonium Compounds; D014867:Water; D013779:Tetrodotoxin; D012965:Sodium Chloride; D001285:Atropine; C004991:benzoquinonium; D008784:Methysergide