Forearm vascular responses to baroreceptor unloading at the onset of dynamic exercise
| Autor: | G. W. Mack, Xiangrong Shi, Ethan R. Nadel, Takeshi Nishiyasu |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Adult
Male medicine.medical_specialty Baroreceptor Adolescent Physiology Rest Blood Pressure Pressoreceptors Physical exercise Baroreflex Forearm Heart Rate Physiology (medical) Internal medicine Supine Position Humans Medicine Exercise Skin Lower Body Negative Pressure business.industry Muscles Temperature Stroke Volume medicine.anatomical_structure Regional Blood Flow Circulatory system Cardiology Reflex Physical therapy Vascular Resistance medicine.symptom business Vasoconstriction Blood vessel |
| Zdroj: | Journal of Applied Physiology. 75:979-985 |
| ISSN: | 1522-1601 8750-7587 |
| Popis: | To determine the extent to which reflexes accompanying muscular exercise (associated with central command) interact with cardiopulmonary (CP) baroreceptor-mediated reflexes controlling forearm vascular resistance (FVR), we examined the forearm vasoconstrictor response at the onset of dynamic exercise, with and without CP baroreflex unloading, in 10 physically active men. CP baroreceptors were unloaded by application of lower body negative pressure (LBNP) at rest and during five 4-min bouts of supine exercise at 25 and 32 degrees C. Exercise intensities were 10 (essentially no load) and 100 W, and LBNP was applied at -10, -20, -30, and -40 mmHg during rest and at -20 and -40 mmHg during exercise. Resting FVR was 33.0 +/- 3.2 and 14.0 +/- 2.7 resistance units, and cardiac stroke volume (SV) was 117 +/- 7 and 126 +/- 9 ml/beat at 25 and 32 degrees C, respectively. We found a linear relationship between the increase in FVR and decrease in SV during LBNP; the slope of the relationship was significantly lower at 32 degrees C (FVR = 51.7–0.29SV) than at 25 degrees C (FVR = 123–0.79SV). At the onset of 100-W exercise without LBNP, FVR increased significantly to 50.2 +/- 9.0 and 21.2 +/- 3.2 units at 25 and 32 degrees C, respectively, whereas SV was unchanged. Application of -40-mmHg LBNP reduced SV significantly to 68 +/- 5 and 71 +/- 6 ml/beat and increased FVR significantly to 89.0 +/- 11.3 and 36.3 +/- 7.6 units at 25 and 32 degrees C, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
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