MECHANICAL PERFORMANCE OF AN IN-SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5-DEGREES-C AND 15-DEGREES-C

A.P. Farrell, CE FRANKLIN, Peter Arthur, H Thorarensen, KL COUSINS

Research output: Contribution to journalArticle

Abstract

We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5 degrees C and 15 degrees C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15 degrees C and a spontaneous heart rate of 23.4 beats min(-1), maximum stroke volume was 2.54 mlkg(-1) body mass, maximum cardiac output was 62.5 mlmin(-1) kg(-1) and maximum cardiac myocardial power output was 1.50 mW g(-1) ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor.

At 5 degrees C, the spontaneous heart rate (8.1 beats min(-1)) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 mlkg(-1)) was not significantly reduced compared with the value at 15 degrees C. The significantly lower maximum values for cardiac output (18.9 mlmin(-1) kg(-1)) and power output (0.39 mW g(-1) ventricular mass) at 5 degrees C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy.

Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5 degrees C than at 15 degrees C. The maximum anoxic cardiac power output value at 15 degrees C (0.77 mW g(-1) ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.

Original languageEnglish
Pages (from-to)207-229
Number of pages23
JournalThe Journal of Experimental Biology
Volume191
Publication statusPublished - Jun 1994

Cite this

@article{0240f83926214e8cbb3199193de6e121,
title = "MECHANICAL PERFORMANCE OF AN IN-SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5-DEGREES-C AND 15-DEGREES-C",
abstract = "We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5 degrees C and 15 degrees C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15 degrees C and a spontaneous heart rate of 23.4 beats min(-1), maximum stroke volume was 2.54 mlkg(-1) body mass, maximum cardiac output was 62.5 mlmin(-1) kg(-1) and maximum cardiac myocardial power output was 1.50 mW g(-1) ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor.At 5 degrees C, the spontaneous heart rate (8.1 beats min(-1)) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 mlkg(-1)) was not significantly reduced compared with the value at 15 degrees C. The significantly lower maximum values for cardiac output (18.9 mlmin(-1) kg(-1)) and power output (0.39 mW g(-1) ventricular mass) at 5 degrees C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy.Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5 degrees C than at 15 degrees C. The maximum anoxic cardiac power output value at 15 degrees C (0.77 mW g(-1) ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.",
keywords = "TEMPERATURE, HEART, ANOXIA, HEART RATE, CARDIAC OUTPUT, TURTLE, CHRYSEMYS SCRIPTA, CORONARY-ARTERY PERFUSION, BLOOD ACID-BASE, CARDIAC-PERFORMANCE, TROUT HEART, PICTA-BELLII, CARDIOVASCULAR FUNCTION, PROLONGED SUBMERGENCE, CHELONIA-MYDAS, RAINBOW-TROUT, IONIC CHANGES",
author = "A.P. Farrell and CE FRANKLIN and Peter Arthur and H Thorarensen and KL COUSINS",
year = "1994",
month = "6",
language = "English",
volume = "191",
pages = "207--229",
journal = "The Journal of Experimental Biology",
issn = "0022-0949",
publisher = "The Company of Biologists",

}

MECHANICAL PERFORMANCE OF AN IN-SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5-DEGREES-C AND 15-DEGREES-C. / Farrell, A.P.; FRANKLIN, CE; Arthur, Peter; Thorarensen, H; COUSINS, KL.

In: The Journal of Experimental Biology, Vol. 191, 06.1994, p. 207-229.

Research output: Contribution to journalArticle

TY - JOUR

T1 - MECHANICAL PERFORMANCE OF AN IN-SITU PERFUSED HEART FROM THE TURTLE CHRYSEMYS SCRIPTA DURING NORMOXIA AND ANOXIA AT 5-DEGREES-C AND 15-DEGREES-C

AU - Farrell, A.P.

AU - FRANKLIN, CE

AU - Arthur, Peter

AU - Thorarensen, H

AU - COUSINS, KL

PY - 1994/6

Y1 - 1994/6

N2 - We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5 degrees C and 15 degrees C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15 degrees C and a spontaneous heart rate of 23.4 beats min(-1), maximum stroke volume was 2.54 mlkg(-1) body mass, maximum cardiac output was 62.5 mlmin(-1) kg(-1) and maximum cardiac myocardial power output was 1.50 mW g(-1) ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor.At 5 degrees C, the spontaneous heart rate (8.1 beats min(-1)) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 mlkg(-1)) was not significantly reduced compared with the value at 15 degrees C. The significantly lower maximum values for cardiac output (18.9 mlmin(-1) kg(-1)) and power output (0.39 mW g(-1) ventricular mass) at 5 degrees C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy.Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5 degrees C than at 15 degrees C. The maximum anoxic cardiac power output value at 15 degrees C (0.77 mW g(-1) ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.

AB - We developed an in situ perfused turtle (Chrysemys scripta) heart preparation to study its intrinsic mechanical properties at 5 degrees C and 15 degrees C using normoxic and anoxic perfusion conditions. The in situ preparation proved durable and stable. At 15 degrees C and a spontaneous heart rate of 23.4 beats min(-1), maximum stroke volume was 2.54 mlkg(-1) body mass, maximum cardiac output was 62.5 mlmin(-1) kg(-1) and maximum cardiac myocardial power output was 1.50 mW g(-1) ventricular mass. There was good agreement between these values and those previously obtained in vivo. Furthermore, since the maximum stroke volume observed here was numerically equivalent to that observed in ventilating C. scripta in vivo, it seems likely that C. scripta has little scope to increase stroke volume to a level much beyond that observed in the resting animal through intrinsic mechanisms alone. The ability of the perfused turtle heart to maintain stroke volume when diastolic afterload was raised (homeometric regulation) was relatively poor.At 5 degrees C, the spontaneous heart rate (8.1 beats min(-1)) was threefold lower and homeometric regulation was impaired, but maximum stroke volume (2.25 mlkg(-1)) was not significantly reduced compared with the value at 15 degrees C. The significantly lower maximum values for cardiac output (18.9 mlmin(-1) kg(-1)) and power output (0.39 mW g(-1) ventricular mass) at 5 degrees C were largely related to pronounced negative chronotropy with only a relatively small negative inotropy.Anoxia had weak negative chronotropic effects and marked negative inotropic effects at both temperatures. Negative inotropy affected pressure development to a greater degree than maximum flow and this difference was more pronounced at 5 degrees C than at 15 degrees C. The maximum anoxic cardiac power output value at 15 degrees C (0.77 mW g(-1) ventricular mass) was not that different from values previously obtained for the performance of anoxic rainbow trout and hagfish hearts. In view of this, we conclude that the ability of turtles to overwinter under anoxic conditions depends more on their ability to reduce cardiac work to a level that can be supported through glycolysis than on their cardiac glycolytic potential being exceptional.

KW - TEMPERATURE

KW - HEART

KW - ANOXIA

KW - HEART RATE

KW - CARDIAC OUTPUT

KW - TURTLE

KW - CHRYSEMYS SCRIPTA

KW - CORONARY-ARTERY PERFUSION

KW - BLOOD ACID-BASE

KW - CARDIAC-PERFORMANCE

KW - TROUT HEART

KW - PICTA-BELLII

KW - CARDIOVASCULAR FUNCTION

KW - PROLONGED SUBMERGENCE

KW - CHELONIA-MYDAS

KW - RAINBOW-TROUT

KW - IONIC CHANGES

M3 - Article

VL - 191

SP - 207

EP - 229

JO - The Journal of Experimental Biology

JF - The Journal of Experimental Biology

SN - 0022-0949

ER -