In isolated rat hearts perfused with HEPES and red blood cell-enriched buffers, we examined changes in left ventricular pressure induced by increases in heart rate or infusion of adenosine to investigate whether the negative force-frequency relation and the positive inotropic effect of adenosine are related to an inadequate oxygen supply provided by crystalloid perfusates. Hearts perfused with HEPES buffer at a constant flow demonstrated a negative force-frequency relation, whereas hearts perfused with red blood cell-enriched buffer exhibited a positive force-frequency relation. In contrast, HEPES buffer-perfused hearts showed a concentration-dependent increase in left ventricular systolic pressure [EC50 = 7.0 +/- 1.2 nM, maximal effect (Emax) = 104 +/- 2 and 84 +/- 2 mmHg at 0.1 microM and baseline, respectively] in response to adenosine, whereas hearts perfused with red blood cell-enriched buffer showed no change in left ventricular pressure. The positive inotropic effect of adenosine correlated with the simultaneous reduction in heart rate (r = 0.67, P < 0.01; EC50 = 3.8 +/- 1.4 nM, baseline 228 +/- 21 beats/min to a minimum of 183 +/- 22 beats/min at 0.1 microM) and was abolished in isolated hearts paced to suppress the adenosine-induced bradycardia. In conclusion, these results indicate that the negative force-frequency relation and the positive inotropic effect of adenosine in the isolated rat heart are related to myocardial hypoxia, rather than functional peculiarities of the rat heart.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1152/ajpheart.00896.2003 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Simultaneous electro-dynamic stimulation accelerates maturation of engineered cardiac tissues generated by human iPS cells.
Biochem Biophys Res Commun
November 2024
Clinical Translational Research Program, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan; Department of Cardiovascular Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan. Electronic address:
Electrical and dynamic stimulation are commonly employed to enhance the maturation of engineered cardiac tissue (ECT) derived from human induced pluripotent stem cells (iPSCs), reflecting the physiological environment of the heart. While electrical stimulation mimics natural bioelectrical signals and dynamic stimulation replicates mechanical forces, the combined effects of these stimuli on ECT maturation have not been thoroughly explored. We hypothesized that simultaneous electro-dynamic stimulation would enhance ECT maturation and function more effectively than either stimulus alone.
View Article and Find Full Text PDFThe effects of nickel chloride on papillary muscle contractility under normothermic and hypothermic conditions: Comparison of active and hibernating ground squirrels (Urocitellus undulatus) with Wistar rats.
J Therm Biol
January 2024
Department of Psychology and Neuroscience, Temple University, Weiss Hall, 1701 North 13th Street, Philadelphia, PA, 19122, USA. Electronic address:
Extracellular Ca plays a pivotal role in the regulation of cardiac contractility under normal and extreme conditions. Here, by using nickel chloride (NiCl), a non-specific blocker of extracellular Ca influx, we studied the input of extracellular Ca on the regulation of papillary muscle (PM) contractility under normal and hypothermic conditions in ground squirrels (GS), and rats. By measuring isometric force of contraction, we studied how NiCl affects force-frequency relationship and the rest effect in PM of these species at 30 °C and 10 °C.
View Article and Find Full Text PDFNeuromechanical characterization of the abductor hallucis and its potential role in upright postural control.
Appl Physiol Nutr Metab
March 2024
School of Health and Exercise Sciences, University of British Columbia-Okanagan, Kelowna, BC, Canada.
There is growing evidence to support a role for the abductor hallucis (AH) in standing balance control; however, functional properties of the muscle that may provide more insight into AH's specific contribution to upright posture have yet to be characterized. This study was conducted to quantify functional neuromechanical properties of the AH and correlate the measures with standing balance variables. We quantified strength and voluntary activation during maximal voluntary isometric contractions of the great toe abductor in nine (3 females and 6 males) healthy, young participants.
View Article and Find Full Text PDFGenetic deletion of Kvβ2 (AKR6) causes loss of muscle function and increased inflammation in mice.
Front Aging
June 2023
Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States.
The voltage-gated potassium channels (Kv) are complex ion channels with distinct roles in neurotransmission, electrical conductivity of the heart, and smooth and striated muscle functions. Previously, we demonstrated that deletion of Kvβ2 in mice results in decreased Pax7 protein levels, hindlimb muscles and body weights, and fiber type switching. In the present study, we tested the hypothesis that Kvβ2 regulates skeletal muscle function in mice.
View Article and Find Full Text PDFCellular Biomechanic Impairment in Cardiomyocytes Carrying the Progeria Mutation: An Atomic Force Microscopy Investigation.
Langmuir
December 2022
Cardiovascular Institute & Adult Medical Genetics, University of Colorado Denver Anschutz Medical Campus, Aurora, Colorado80045, United States.
Given the clinical effect of progeria syndrome, understanding the cell mechanical behavior of this pathology could benefit the patient's treatment. Progeria patients show a point mutation in the lamin A/C gene (LMNA), which could change the cell's biomechanical properties. This paper reports a mechano-dynamic analysis of a progeria mutation (c.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!