AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 3 602-R608, Copyright © 1992 by American Physiological Society
Development of blood pressure and cardiac reflexes in the frog Pseudis paradoxsus
W. W. Burggren, J. E. Bicudo, M. L. Glass and A. S. Abe
Department of Biological Sciences, University of Nevada, Las Vegas 89154.
Systemic arterial blood pressure and heart rate (fH) were measured in
unanesthetized, unrestrained larvae and adults of the paradoxical frog,
Pseudis paradoxus from Sao Paulo State in Brazil. Four developmental groups
were used, representing the complete transition from aquatic larvae to
primarily air-breathing adults. fH (49-66 beats/min) was not significantly
affected by development, whereas mean arterial blood pressure was strongly
affected, being lowest in the stage 37-39 larvae (10 mmHg), intermediate in
the stage 44-45 larvae (18 mmHg), and highest in the juveniles and adults
(31 and 30 mmHg, respectively). Blood pressure was not significantly
correlated with body mass, which was greatest in the youngest larvae and
smallest in the juveniles. In the youngest larvae studied (stages 37-39),
lung ventilation was infrequent, causing a slight decrease in arterial
blood pressure but no change in heart rate. Lung ventilation was more
frequent in stages 44-45 larvae and nearly continuous in juveniles and
adults floating at the surface. Bradycardia during both forced and
voluntary diving was observed in almost every advanced larva, juvenile, and
adult but in only one of four young larvae. Developmentally related changes
in blood pressure were not complete until metamorphosis, whereas diving
bradycardia was present at an earlier stage.
