Claude JULIEN

Pharm.D. 1983, Ph.D. 1988

Université Claude Bernard Lyon 1

 

Research Director, CNRS

Cardiovascular Physiology & Pharmacology

Faculty of Pharmacy

8 av. Rockefeller

69008 LYON, FRANCE

 

Tel : 33 478 77 70 72

Fax : 33 478 77 71 18

 

E-Mail contact me

 
 
 
Research Interests
 

There is considerable evidence that an exaggerated variability of blood pressure can initiate and aggravate end-organ damage in hypertension and other cardiovascular diseases. The feedback system that is mainly responsible for controlling blood pressure variability is the arterial baroreceptor reflex. In the past few years, we have developed and used rat models in which the baroreflex loop has been opened at different levels. By simultaneously recording cardiovascular variables (blood pressure and either cardiac output, regional blood flows, or renal sympathetic nerve activity) in the conscious rat, and with the use of computer-aided analyses in both the time- and frequency-domains, we have been able to show that:

  1. the control of BP variability depends on the continuous interactions between slow hemodynamic perturbations (changes in stroke volume, active vasodilatations in the skeletal muscles, autoregulatory responses of regional circulations…) and baroreflex adjustments of sympathetic vascular tone;

  2. an appropriate control of blood pressure variability at low frequencies is achieved at the cost of instability (feedback oscillations, usually termed Mayer waves) at a higher frequency, referred to as the resonance frequency of the baroreflex loop.

We have recently proposed to derive a continuous index of sympathetic baroreflex sensitivity by computing the transfer function between cardiac-related oscillations of sympathetic nerve activity and pulse pressure. The first findings indicate that sympathetic baroreflex sensitivity varies continuously over time under physiological conditions.

 

 
Selected publications (All)
 
  • A. Revel, V. Oréa, B. Chapuis, C. Barrès, C. Julien. Role of the sympathetic nervous system in cerebrovascular responses to air-jet stress in rats. Stress 15:115-120, 2012.

  • C. Gallet, B. Chapuis, C. Barrès, C. Julien. Time-frequency analysis of the baroreflex control of renal sympathetic nerve activity in the rat. J Neurosci Methods 198:336-343, 2011.

  • B. Chapuis, V. Oréa, C. Barrès, C. Julien. Very high frequency components of renal sympathetic nerve activity in conscious rats. Auton Neurosci 152:55-59, 2010.

  • R. Kanbar, B. Chapuis, V. Oréa, C. Barrès, C. Julien. Baroreflex control of lumbar and renal sympathetic nerve activity in conscious rats. Am J Physiol Regul Integr Comp Physiol 295:R8-R14, 2008.

  • R. Kanbar, V. Oréa, B. Chapuis, C. Barrès, C. Julien. A transfer function method for the continuous assessment of baroreflex control of renal sympathetic nerve activity in rats. Am J Physiol Regul Integr Comp Physiol 293: 1938-1946, 2007.

  • V. Oréa, R. Kanbar, B. Chapuis, C. Barrès, C. Julien. Transfer function analysis between arterial pressure and renal sympathetic nerve activity at cardiac pacing frequencies in the rat. J Appl Physiol 102: 1034-1040, 2007.

  • R. Kanbar, V. Oréa, C. Barrès, C. Julien. Baroreflex control of renal sympathetic nerve activity during air-jet stress in rats. Am J Physiol Regul Integr Comp Physiol 292: R362-R367, 2007.

  • C. Julien. The enigma of Mayer waves: Facts and models. Cardiovasc Res 70: 12-21, 2006.

  • L. Emonnot, C. Bakhos, B. Chapuis, V. Oréa, C. Barrès, C. Julien. Role of purinergic cotransmission in the sympathetic control of arterial pressure variability in conscious rats. Am J Physiol Regul Integr Comp Physiol 291: R736-R741, 2006.

  • D. Bertram, V. Oréa, B. Chapuis, C. Barrès, C. Julien. Differential responses of frequency components of renal sympathetic nerve activity to arterial pressure changes in conscious rats. Am J Physiol Regul Integr Comp Physiol 289: R1074-R1082, 2005.

  • B. Chapuis, E. Vidal-Petiot, V. Oréa, C. Barrès, C. Julien. Linear modelling analysis of baroreflex control of arterial pressure variability. J Physiol 559: 639-649, 2004.

  • C. Barrès, Y. Cheng, C. Julien. Steady-state and dynamic responses of renal sympathetic nerve activity to air jet stress in sinoaortic denervated rats. Hypertension 43: 629-635, 2004.

  • C. Julien, B. Chapuis, Y. Cheng, C. Barrès. Dynamic interactions between arterial pressure and sympathetic nerve activity: role of arterial baroreceptors. Am J Physiol Regul Integr Comp Physiol 285: R834-R841, 2003.

  • E. Petiot, C. Barrès, B. Chapuis, C. Julien. Frequency response of renal sympathetic nervous activity to aortic depressor nerve stimulation in the anaesthetized rat. J Physiol 537: 949-959, 2001.

  • S.L.S. Pires, C. Barrès, J. Sassard, C. Julien. Renal blood flow dynamics and arterial pressure lability in the conscious rat. Hypertension 38: 147-152, 2001.

  • D. Bertram, C. Barrès, Y. Cheng, C. Julien. Norepinephrine reuptake, baroreflex dynamics and arterial pressure variability in rats. Am J Physiol Regulatory Integrative Comp Physiol 279: R1257-R1267, 2000.

  •  D. Bertram, C. Barrès, G. Cuisinaud, C. Julien. The arterial baroreceptor reflex of the rat exhibits positive feedback properties at the frequency of Mayer waves. J Physiol 513: 251-261, 1998.

  • R. Létienne, C. Barrès, C. Cerutti, C. Julien. Short-term haemodynamic variability in the conscious areflexic rat. J Physiol 506: 263-274, 1998.

 

Last modified: January 24 2012

 

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