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Comparison of contractile performance of canine atrial and ventricular muscles.
Metadata
Journalcirculation research14.467Date
1975-Dec
Publication Type
Research Support, U.S. Gov't, P.H.S.
Journal Article
Comparative Study
Volume
1975-Dec / 37 : 762-71
Author
Urthaler F , Walker AA , Hefner LL , James TN
DoiPMIDMESH
Animals
Atrial Function
Dogs
Electric Stimulation
Female
Humans
Hydrogen-Ion Concentration
In Vitro Techniques
Male
Myocardial Contraction
Temperature
Ventricular Function
Abstract
This study compared the contractile performance of a canine right atrial trabecula with that of a macroscopically indistinguishable trabecula isolated from the right ventricular apex. The heart was removed from nine mongrel puppies weighing 6-8 kg and placed in Krebs-Ringer's bicarbonate solution. The bathing solution contained only 1.25 mmoles of Ca2+ and was bubbled with a 95% O2-5% CO2 gas mixture. Each atrial trabecula was specially selected from the right atrial appendage. Histologically, these trabeculae showed a remarkable longitudinal orientation of the fibers. At Lmax (the length of the muscle at which developed tension was maximum) under identical conditions of temperature, rate of stimulation, ionic milieu, pH, and O2 and CO2 supply, right atrial trabeculae achieved the same developed and total tensions but in a much shorter time than did ventricular trabeculae. In both muscle groups the maximum developed tension averaged about 2.5 g/mm2. Since Lo (expressed as a fraction of Lmax) was less in atrial muscle than it was in ventribular muscle, we concluded that atrial muscle can be stretched considerably more than can ventricular muscle before optimum length is reached. At any given initial muscle length, the maximum of tension rise for atrial trabeculae amounted to at least twice that for ventricular trabeculae. At any given load up to 1.5 g/mm2, the maximum velocity of shortening of an atrial trabecula was about three to four times that of a ventricular trabecula. These results collectively indicate that the contractile performance of the right atrial muscle is in many respects superior to that of the right ventricle, at least under the conditions of these experiments.
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14.5
Circ Rescirculation research
Metadata
LocationUnited States
FromLIPPINCOTT WILLIAMS & WILKINS

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