Force-frequency effect is a powerful determinant of myocardial contractility in the mouse

Journal Article (Journal Article)

The effects of heart rate (HR) on myocardial contractility in the mouse heart in situ were first investigated in open-chest mice (n = 7) by left ventricular (LV) catheter-tip micromanometry. HR %vas first slowed with a sinus node inhibitor (zatebradine), and atrial pacing to progressively increase the HR caused a positive inotropic response (assessed by maximum positive first derivative of LV pressure, LV dP/d«max) up to a HR of 282 beats/min with the onset of a descending limb of the forcefrequency relation (FFR) at 332 beats/min. β-Adrenergic receptor stimulation (dobutamine) shifted upward and significantly steepened the positive FFR and increased HR at the onset of the descending limb to 402 beats/min. HR and LV dP/d-4max were then studied in closed-chest mice without pacing during recovery from anesthesia (n = 7), and during rest and intermittent physical activity the FFR was linear and positive up to 600 beats/min. HR was then progressively slowed with zatebradine, and the points at rest and during activity fell on the same linear relation. Thus we conclude the following: 1 ) in the open-chest anesthetized mouse, a positive FFR was amplified by β-adrenergic receptor stimulation, and 2) in the mouse recovering from anesthesia the sinus node rate remained a critical determinant of myocardial contractility, without a descending limb of the FFR. Copyright ©1997 the American Physiological Society.

Duke Authors

Cited Authors

  • Palakodeti, V; Samuel, OH; Oh, BH; Mao, LAN; Kongo, M; Peterson, KL; Ross, J

Published Date

  • December 1, 1997

Published In

Volume / Issue

  • 42 / 3

International Standard Serial Number (ISSN)

  • 0363-6135

Citation Source

  • Scopus