Carotid and aortic baroreflexes of the rat: I. Open-loop steady-state properties and blood pressure variability
| Autor: | Barry R. Dworkin, Xiaorui Tang, Susan Dworkin |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Baroreceptor
Physiology Hemodynamics Blood Pressure Baroreflex Heart Rate Physiology (medical) medicine.artery medicine Animals Rats Long-Evans Splanchnic Circulation Aorta Skin business.industry Carotid sinus Electric Conductivity Sinus of Valsalva Denervation Rats Femoral Artery medicine.anatomical_structure Blood pressure Carotid Arteries Anesthesia Circulatory system Female business Venous Pressure Blood vessel |
| Zdroj: | American journal of physiology. Regulatory, integrative and comparative physiology. 279(5) |
| ISSN: | 0363-6119 |
| Popis: | To characterize the baroreflex in central nervous system-intact neuromuscular-blocked rats, we measured the vascular and cardiac responses and compared direct stimulation of the aortic depressor nerve (ADN) with a capacitance electrode (differentially activating either A or A + C fibers) to carotid sinus pressure with a micro-balloon (SINUS). One-thousand-two-hundred-ninety-seven open-loop measurements of systolic blood pressure (SBP), heart rate, venous pressure (VBP), and mesenteric (msBF), femoral (fmBF), and skin (skBF) blood flow were completed; the linear range of the effects was determined for each response and stimulus mode. The rats were sinoaortic denervated (SAD). The open-loop stimulation effect was very stable; e.g., the mean effect of 790 ADN stimulations during >7 days was −9.8 mmHg, with an average drift of +0.001 mmHg/h. In contrast, there was large variability of the SBP baseline (e.g., SD = ±10.9), which was due to SAD (±6.3 to ±16.3 mmHg, t = −13.9, df = 4, P < 0.0002) and was reversed by ganglionic block (±10.8 to ± 2.9 mmHg, t = −12.9, df = 3, P < 0.001). The ADN stimuli produced larger depressor responses than sinus stimuli (−66 vs. −45 mmHg); all component responses paralleled the magnitude of the SBP effect, except interbeat interval (IBI), for which the ADN ΔIBI was ≈10 times that of SINUS. For all stimuli, fmBF increased and msBF did not. Mesenteric and femoral vascular conductance both increased, whereas VBP decreased and skBF followed SBP. We found that for all baroreflex response components, with the exception of SINUS-elicited ΔIBI, there was an orderly, substantially linear, relationship between stimulus strength and response magnitude. |
| Databáze: | OpenAIRE |
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