We tested the hypothesis that vagal withdrawal and increased venous return interact in determining the rapid cardiac output response (Phase I) at exercise onset. We used lower body negative pressure (LBNP) to increase blood dislocation to the heart by muscle pump action and simultaneously reduce resting vagal activity. At exercise start, we expected larger response amplitude for stroke volume and smaller for heart rate at progressively stronger LBNP levels, so that the cardiac output response would remain unchanged. Ten subjects performed 50 W exercise supine in Control condition and during -45 mmHg LBNP exposure. On single beat basis, we measured heart rate (HR), stroke volume (SV), and we calculated cardiac output (CO). We computed Phase I response amplitudes (A1) using an exponential model. SV A1 was higher under LBNP than in Control (p < 0.05). Conversely, the A1 of HR, was 23 ± 56 % lower under LBNP than in Control (although NS). Since these changes tended to compensate each other, the A1 for CO was unaffected by LBNP. The rapid SV kinetics at exercise onset is compatible with an effect of increased venous return, whereas the vagal withdrawal conjecture cannot be dismissed for HR kinetics. The rapid CO response may indeed be the result of two independent yet parallel mechanisms, as hypothesized, one acting on SV, the other on HR

Fontolliet, T., Fagoni, N., Bruseghini, P., Capelli, C., Lador, F., Moia C1 Tam, E., Bringard, A., Ferretti, G., The effect of lower body negative pressure on phase 1 cardiovascular responses at exercise onset in healthy humans, Abstract de <<Joint Meeting Federation of European Physiological Societies (FEPS) and Italian Physiological Society (SIF)>>, (Bologna, 10-13 September 2019 ), <<ACTA PHYSIOLOGICA>>, 2019; 227 (s718): 175-176 [http://hdl.handle.net/10807/215557]

The effect of lower body negative pressure on phase 1 cardiovascular responses at exercise onset in healthy humans

Bruseghini, P;
2019

Abstract

We tested the hypothesis that vagal withdrawal and increased venous return interact in determining the rapid cardiac output response (Phase I) at exercise onset. We used lower body negative pressure (LBNP) to increase blood dislocation to the heart by muscle pump action and simultaneously reduce resting vagal activity. At exercise start, we expected larger response amplitude for stroke volume and smaller for heart rate at progressively stronger LBNP levels, so that the cardiac output response would remain unchanged. Ten subjects performed 50 W exercise supine in Control condition and during -45 mmHg LBNP exposure. On single beat basis, we measured heart rate (HR), stroke volume (SV), and we calculated cardiac output (CO). We computed Phase I response amplitudes (A1) using an exponential model. SV A1 was higher under LBNP than in Control (p < 0.05). Conversely, the A1 of HR, was 23 ± 56 % lower under LBNP than in Control (although NS). Since these changes tended to compensate each other, the A1 for CO was unaffected by LBNP. The rapid SV kinetics at exercise onset is compatible with an effect of increased venous return, whereas the vagal withdrawal conjecture cannot be dismissed for HR kinetics. The rapid CO response may indeed be the result of two independent yet parallel mechanisms, as hypothesized, one acting on SV, the other on HR
Inglese
Fontolliet, T., Fagoni, N., Bruseghini, P., Capelli, C., Lador, F., Moia C1 Tam, E., Bringard, A., Ferretti, G., The effect of lower body negative pressure on phase 1 cardiovascular responses at exercise onset in healthy humans, Abstract de <<Joint Meeting Federation of European Physiological Societies (FEPS) and Italian Physiological Society (SIF)>>, (Bologna, 10-13 September 2019 ), <<ACTA PHYSIOLOGICA>>, 2019; 227 (s718): 175-176 [http://hdl.handle.net/10807/215557]
File in questo prodotto:
File Dimensione Formato  
Sif feps 2019 font bru.pdf

accesso aperto

Licenza: Non specificato
Dimensione 125.63 kB
Formato Adobe PDF
125.63 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10807/215557
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact