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Titolo:
Differential baroreflex control of heart rate in sedentary and aerobicallyfit individuals
Autore:
Smith, SA; Querry, RG; Fadel, PJ; Welch-OConnor, RM; Olivencia-Yurvati, A; Shi, XR; Raven, PB;
Indirizzi:
Univ N Texas, Hlth Sci Ctr, Dept Integrat Physiol, Ft Worth, TX 76107 USA Univ N Texas Ft Worth TX USA 76107 tegrat Physiol, Ft Worth, TX 76107 USA Univ N Texas, Hlth Sci Ctr, Cardiovasc Res Inst, Ft Worth, TX 76107 USA Univ N Texas Ft Worth TX USA 76107 ovasc Res Inst, Ft Worth, TX 76107 USA
Titolo Testata:
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
fascicolo: 8, volume: 32, anno: 2000,
pagine: 1419 - 1430
SICI:
0195-9131(200008)32:8<1419:DBCOHR>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
CENTRAL VENOUS-PRESSURE; CAROTID BAROREFLEX; ORTHOSTATIC INTOLERANCE; REFLEX RESPONSES; PHYSICAL-FITNESS; BLOOD-PRESSURE; CARDIAC REFLEX; EXERCISE; MEN; TOLERANCE;
Keywords:
autonomic control; fitness; baroreceptors; inhibitory interaction;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Smith, SA Univ N Texas, Hlth Sci Ctr, Dept Integrat Physiol, 3500 Camp Bowie Blvd, Ft Worth, TX 76107 USA Univ N Texas 3500 Camp Bowie Blvd Ft Worth TX USA 76107 6107 USA
Citazione:
S.A. Smith et al., "Differential baroreflex control of heart rate in sedentary and aerobicallyfit individuals", MED SCI SPT, 32(8), 2000, pp. 1419-1430

Abstract

Purpose: We compared arterial, aortic, and carotid-cardiac baroreflex sensitivity in eight average fit (maximal oxygen uptake, (V) over dot (2max) = 42.2 +/- 1.9 mL.kg(-1).min(-1)) and eight high fit ((V) over dot (2max) = 61.9 +/- 2.2 mL.kg(-1).min(-1)) healthy young adults. Methods: Arterial and aortic (ABR) baroreflex functions were assessed utilizing hypo- and hyper-tensive challenges induced by graded bolus injections of sodium nitroprusside (SN) and phenylephrine (PE), respectively. Carotid baroreflex (CBR) sensitivity was determined using ramped 5-s pulses of both pressure and suction delivered to the carotid sinus via a neck chamber collar, independent of drug administration. Results: During vasoactive drug injection, mean arterialpressure (MAP) was similarly altered in average fit (AF) and high fit II-IF) groups. However, the heart rate (HR) response range of the arterial baroreflex was significantly attenuated (P < 0.05) in HF (31 +/- 4 beats min-l)compared with AF individuals (46 +/- 4 beats min(-1)). When sustained necksuction and pressure were applied to counteract altered carotid sinus pressure during SN and PE administration, isolating the ABR response, the response range remained diminished (P 4 0.05) in the HF population (24 +/- 3 beats min(-1)) compared with the AF group (41 +/- 4 beats.min(-1)). During CBRperturbation, the HF (14 +/- 1 beats.min(-1)) and AF (16 +/- 1 beats.min(-1)) response ranges were similar. The arterial baroreflex response range was significantly less than the simple sum of the CBR and ABR (HF, 38 +/- 3 beats.min(-1) and AF, 57 +/- 4 beats.min(-1)) in both fitness groups. Conclusions: These data confirm that reductions in arterial-cardiac reflex sensitivity are mediated by diminished ABR function. More importantly, these datasuggest that the integrative relationship between the ABR and CBR contributing to arterial baroreflex control of HR is inhibitory in nature and not altered by exercise training.

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Documento generato il 03/12/20 alle ore 06:04:24