A constant temperature perfusion system for myocardial energetics

Niesler, R. A.; Axon, D W; Eggert, Martin

doi:10.1088/0031-9155/26/6/006

Cited by 2 publications

(1 citation statement)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The heart calorimeter system was assembled as previously described (25,26) and operated at 37 ~ Male Wistar rats, weighing 400-500 g and fed ad libitum, were used. Each animal was anaesthetized with ether and then heparin (200 IU) was administered into the femoral vein.…”

Section: Procedures and Materialsmentioning

confidence: 99%

The measurement of heat production, mechanical power, and oxygen consumption of the isolated working rat heart

1985

View full text Add to dashboard Cite

The article describes a method for monitoring the total energy output and oxygen uptake of isolated perfused rat hearts with working left ventricles. Twenty-two unpaced hearts (rates 4-4.5 bs-1) were separately investigated inside a flow micro-calorimeter (one minute for 90% thermal response) at 37 degrees C. They pumped fluid into an artificial arterial system with adjustable linear peripheral resistance and variable volume compliance. After about 20-40 minutes a steady state period was achieved and most of the hearts continued to operate in this state for a further 40-100 minutes. In the steady state the outputs were in the ranges of 30-50 mJ s-1g-1 mechanical power (per gram tissue dry weight) and 100-300 mJ s-1g-1 heat production at an oxygen uptake of between 0.01 and 0.02 cm3 O2 s-1g-1. This resulted in approximately constant cardiac outputs between 2 and 4 cm3 s-1g-1 aortic and coronary fluid and stable mechanical efficiencies between 12 and 20%. The energy balance in steady state under a number of defined arterial loads was also analyzed. The hearts attained reproducible maxima of mechanical efficiency at specific loads. Methods to allocate reference points in the energy scheme are discussed. The yield of biochemical energy from the perfusion fluid (utilized for contraction and heat production) was (on average) 21 J per cm3 oxygen consumption (energy equivalent of oxygen). No obvious correlation between this value and the mechanical efficiency was evident.

show abstract

Section: Procedures and Materialsmentioning

confidence: 99%

The measurement of heat production, mechanical power, and oxygen consumption of the isolated working rat heart

1985

View full text Add to dashboard Cite

show abstract

A flow microcalorimeter system for the measurement of dynamic energy variables of isolated perfused hearts

Niesler

Axon

1981

pmb

View full text Add to dashboard Cite

An isothermic flow microcalorimeter system for fluid rates of 1-50 cm3 min -1 has been developed to measure the total heat flow produced by isolated perfused small animal hearts and its rate of change. The heat, which is absorbed by the perfusion fluid flowing through the coronary capillary system, is detected by passing the coronary effluent through a plate heat exchanger mounted in intimate contact with the internal surface of a gradient layer calorimeter. By employing electrical calibration, this heat flow detector gives a precision of +/- 0.2 m W for average effluent rates of about 15 cm3 min-1. The method provides direct comparison of the biologically produced heat flow with electrically generated energy flows. The response time to step changes in heat flow is 1 min to 90% of the total change. Possible systematic errors are analysed and quantified, using a heart bypass flow technique and a thermoelectric differential temperature meter. The accuracy of the measurement of constant heat sources with the complete system over the range of 5-40 mW is +/- 2% for fluid rates up to 40 cm3 min-1. Measurements with small rat hearts have given absolute values between 17 and 36 mW measured with an accuracy of +/- 3%. The rate of total myocardial energy turnover can be studied with the system.

show abstract

A constant temperature perfusion system for myocardial energetics

Cited by 2 publications

References 12 publications

The measurement of heat production, mechanical power, and oxygen consumption of the isolated working rat heart

The measurement of heat production, mechanical power, and oxygen consumption of the isolated working rat heart

A flow microcalorimeter system for the measurement of dynamic energy variables of isolated perfused hearts

Contact Info

Product

Resources

About