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Norepinephrine reuptake, baroreflex dynamics, and arterial pressure variability in rats
1Département de Physiologie et Pharmacologie Clinique, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5014, Faculté de Pharmacie, Lyon, 69373 France. bertram@rockefeller.univ-lyon1.fr
Summary
Desipramine (DMI) reduces baroreflex gain, decreasing sympathetic nerve activity variability and increasing arterial pressure variability in rats. This suggests DMI impairs the baroreflex loop, affecting cardiovascular regulation.
Area of Science:
- Cardiovascular Physiology
- Neuropharmacology
Background:
- Norepinephrine reuptake inhibitors like desipramine (DMI) impact autonomic nervous system regulation.
- Understanding their effects on baroreflex control is crucial for cardiovascular health.
Purpose of the Study:
- To investigate how desipramine (DMI) affects arterial pressure (AP) and renal sympathetic nerve activity (SNA) variability.
- To determine if DMI alters the dynamic characteristics of the baroreceptor reflex loop.
Main Methods:
- Conscious rats were administered DMI (2 mg/kg iv) to record AP and renal SNA.
- Frequency responses of AP and iliac vascular conductance to nerve stimulation were analyzed in anesthetized rats.
Main Results:
- DMI depressed AP Mayer waves and increased low-frequency AP variability.
- DMI decreased renal SNA variability, particularly oscillations linked to Mayer waves.
- DMI accentuated low-pass filter properties of the baroreceptor reflex transfer function.
Conclusions:
- DMI-induced reduction in baroreflex dynamic gain explains decreased renal SNA variability and increased AP variability.
- The observed "slowing down" of baroreflex responses is not due to DMI's effect on the vascular neuroeffector junction.