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Coronary response to transient increases in transmural pressure
D Casalucci1, L Gastaldi, D Gattullo
1Dipartimento di Scienze Biomediche ed Oncologia Umana, Università di Torino, Italy.
Cardioscience
|September 1, 1991
Summary
Transient increases in aortic blood pressure significantly raised coronary vascular resistance in normally innervated dog hearts, unlike previous findings in vagotomized, beta-blocked dogs. This suggests intact autonomic nerves modulate coronary blood flow responses to pressure changes.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Regulation
- Coronary Circulation
Background:
- Previous studies in beta-blockade and vagal section demonstrated minimal coronary vascular resistance changes during aortic occlusion.
- The response of coronary vascular resistance in normally innervated hearts to transient aortic pressure increases remained unexamined.
Purpose of the Study:
- To investigate the effect of transient aortic pressure increases on coronary vascular resistance in normally innervated, anesthetized dogs.
- To compare these responses with findings in hearts with beta-blockade and vagal section.
Main Methods:
- Experiments conducted on six anesthetized dogs.
- Measurements included aortic root pressure, left ventricular pressure, and left circumflex coronary artery flow.
- Coronary vascular resistance calculated as (Aortic Pressure - Left Ventricular Pressure) / Coronary Flow.
Main Results:
- Normally innervated hearts exhibited significantly lower baseline coronary vascular resistance compared to previous studies.
- Aortic pressure increases during occlusion caused a significant rise in coronary vascular resistance after 10 seconds.
- Coronary vascular resistance increased further upon occlusion release, exceeding levels seen in vagotomized, beta-blocked animals.
Conclusions:
- Normally innervated hearts show a distinct response to transient aortic pressure elevation, with a significant increase in coronary vascular resistance.
- The intact autonomic nervous system appears to modulate vasomotor tone, influencing coronary vascular resistance during pressure fluctuations.
- Lower baseline vasomotor tone in normally innervated hearts may contribute to these observed differences.