Development of adrenergic and cholinergic cardiac control in larvae of the African clawed frog Xenopus laevis.
Physiol Biochem Zool
; 72(3): 328-38, 1999.
Article
en En
| MEDLINE
| ID: mdl-10222327
Cardiac responses (heart rate, stroke volume, and cardiac output) to cholinergic and adrenergic receptor stimulation were investigated in developing larvae of Xenopus laevis from Nieuwkoop and Faber (NF) stage 33/34 (newly hatched) to NF stage 53 (22 d after hatching). Effects on heart rate (fH), stroke volume (SV), and cardiac output (CO) were analyzed using in situ preparations and video-microscopic techniques to record the continually beating heart. The results show that administration of acetylcholine to the heart decreases heart rate as early as NF stage 40. A significant reduction in SV and CO following acetylcholine administration to the heart was found at NF stages 45-53. Epinephrine had no significant effect on fH, SV, or CO at any of the stages investigated. However, an adrenergic tonus on the heart is present already at NF stage 40 (11%). This tonus increases up to a maximum (44%) at NF stages 45-47, when the maximal heart rate is found during development of X. laevis. We conclude that acetylcholine has a negative chronotropic and possibly also inotropic effect on the heart very early in development of X. laevis. We also hypothesize that the high adrenergic tonus found at NF stages 45-47 is responsible, at least in part, for the peak in heart rate seen at these stages.
Buscar en Google
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Fibras Colinérgicas
/
Fibras Adrenérgicas
/
Corazón
Límite:
Animals
Idioma:
En
Revista:
Physiol Biochem Zool
Asunto de la revista:
BIOLOGIA
/
FISIOLOGIA
Año:
1999
Tipo del documento:
Article
País de afiliación:
Suecia
Pais de publicación:
Estados Unidos