title: Cardiac output and peripheral resistance during larval development in the anuran amphibian Xenopus laevis.
abstract: Stroke volume (SV) and cardiac output (CO) were measured in anesthetized larvae of Xenopus laevis from hatching (3 mg) to the end of metamorphosis (approximately 1 g). CO and SV were calculated from videotaped images of the intact beating heart. SV increased from 2.4 x 10(-3) microliters at 3 mg body mass to 7.6 microliters at 1 g. CO increased from 0.25 microliter/min at 3 mg to 623 microliters/min at 1 g. With use of CO, along with arterial pressures from another study [P.-C. L. Hou and W. W. Burggren. Am. J. Physiol. 269 (Regulatory Integrative Comp. Physiol. 38): R1120-R1125, 1995], peripheral resistance and cardiac work were also calculated. Resistance decreased rapidly from 701 peripheral resistance units (PRU, mmHg.s.mm-3) at 3 mg body mass to 79 PRU at 20 mg and gradually declined toward 0.9 PRU at 1 g. Cardiac work increased from 0.06 dyn.mm at 3 mg body mass to 1.27 dyn.mm at 20 mg and then climbed sharply to 717 dyn.mm at 1 g. The general pattern of change in hemodynamic variables (except heart rate) during larval development is similar in Xenopus laevis and chick embryos, suggesting a common pattern for hemodynamic development in vertebrate embryos/larvae.
authors.affiliation: Department of Biology, National Cheng Kung University, Tainan, Taiwan, Republic of China.
authors.forename: P C
authors.initials: PC
authors.lastname: Hou
authors.forename: W W
authors.initials: WW
authors.lastname: Burggren
mesh_terms: D000818:Animals; D002302:Cardiac Output; D006321:Heart / Q000502:physiology; D007814:Larva / Q000502:physiology; D013318:Stroke Volume; D014655:Vascular Resistance; D014982:Xenopus laevis / Q000502:physiology*