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Titolo:
REDUCED SPONTANEOUS BAROREFLEX RESPONSE SLOPE DURING LOWER-BODY NEGATIVE-PRESSURE AFTER 28 DAYS OF HEAD-DOWN BED REST
Autore:
HUGHSON RL; MAILLET A; GHARIB C; FORTRAT JO; YAMAMOTO Y; PAVYLETRAON A; RIVIERE D; GUELL A;
Indirizzi:
UNIV WATERLOO,DEPT KINESIOL WATERLOO N2L 3G1 ON CANADA UNIV LYON 1,DEPT PHYSIOL F-69373 LYON 08 FRANCE MEDES,INST MED & PHYSIOL SPATIALES F-31052 TOULOUSE FRANCE
Titolo Testata:
Journal of applied physiology
fascicolo: 1, volume: 77, anno: 1994,
pagine: 69 - 77
SICI:
8750-7587(1994)77:1<69:RSBRSD>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
BARORECEPTOR-CARDIAC REFLEX; CENTRAL VENOUS-PRESSURE; ARTERIAL BAROREFLEX; BLOOD-PRESSURE; ORTHOSTATIC INTOLERANCE; CAROTID BAROREFLEX; EXERCISE; HUMANS; TOLERANCE; SEQUENCE;
Keywords:
BLOOD PRESSURE; HEART RATE; CARDIOVASCULAR DECONDITIONING; ORTHOSTATIC HYPOTENSION; EXERCISE COUNTERMEASURES; ARTERIAL BAROREFLEX;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
37
Recensione:
Indirizzi per estratti:
Citazione:
R.L. Hughson et al., "REDUCED SPONTANEOUS BAROREFLEX RESPONSE SLOPE DURING LOWER-BODY NEGATIVE-PRESSURE AFTER 28 DAYS OF HEAD-DOWN BED REST", Journal of applied physiology, 77(1), 1994, pp. 69-77

Abstract

Effects of 28 days of continuous 6 degrees head-down tilt bed rest onspontaneous vagally mediated baroreflex response slope were evaluatedfrom beat-by-beat relationships between R-R interval and systolic arterial blood pressure. Twelve healthy men (age 27-42 yr) were assigned to either countermeasure (CM) or no-countermeasure (no-CM) groups. CM consisted of strenuous short-term exercise once per day 6 days/wk fromdays 7 to 28 and lower body negative pressure (LBNP) for 15 min on clays 16, 18, 20, and 22-28. Spontaneous baroreflex slope was evaluated by application of linear regression to sequences of at least three beats in which systolic blood pressure and R-R interval changed in the same direction. Measurements were made pre-, mid- (day 15), and post-bedrest at rest and during progressive LBNP tests (3 min at each of -20,-30, -40, and -50 mmHg). R-R interval decreased progressively and significantly (P < 0.0001) over duration of bed rest. Spontaneous baroreflex slope at rest in pre-bed rest was 18.5 +/- 2.1 ms/mmHg for CM and 14.9 +/- 1.6 ms/ mmHg for no-CM. There was a significant reduction in baroreflex slope as a function of bed rest, and it was further reducedduring LBNP (P < 0.0001). Between CM and no-CM groups differences existed, but these were present pre-bed rest and appeared unaffected by countermeasures. A linear relationship existed between baroreflex slopeand R-R interval (r = 0.61) such that at -50 mmHg of LBNP in post-bed-rest tests baroreflex slopes were 5.4 +/- 0.8 and 5.2 +/- 1.0 ms/mmHgfor CM and no-CM, respectively. Because we saw a linear reduction in spontaneous baroreflex slope as a function of the reduction in R-R interval, we hypothesize that spontaneous baroreflex slope was in part a function of background vagal activity to the heart.

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Documento generato il 03/12/20 alle ore 10:47:50