Evaluation of the arterial baroreflex Peter B. Raven, Ph.D. [PDF]

SLIDE 1

Evaluation of the arterial baroreflex Peter B. Raven, Ph.D. University of North Texas Health Science Center Fort Worth, TX, U.S.A.

SLIDE 2

Methods of Investigating Arterial Baroreflex

1. Valsalva - arterial (aortic + carotid)
2. Carotid massage - carotid
3. Oxford technique - arterial (aortic + carotid)
4. Dynamic baroreflex( sequence technique)- arterial (aortic + carotid)
5. Dynamic baroreflex (transfer function gain ) - arterial (aortic + carotid)
6. Static baroreflex - Carotid baroreflex

i) Rapid Train of NP/NS - carotid baroreflex ii) Building carotid baroreflexes with NP/NS iii) Aortic baroreflex - isolation Pharmacological Mechanical

SLIDE 3

Nitroprusside Phenylephrine BP ABR Cardiac - ∆HR/∆SBP, Vasomotor - ∆MSNA/∆DBP HR MSNA Oxford technique

SLIDE 4

1 min MSNA

A: Normothermia B: Hyperthermia

SBF (unit)

100 200 50 100 50 100 150

BP (mmHg) HR (beats/min) Resp.

Nitroprusside Phenylephrine Phenylephrine Nitroprusside

Cui, Wilson, Crandall, Am. J. Physiol. Reg Comp. Physiol. 2002

SLIDE 5

Systolic Blood Pressure (mmHg)

100 110 120 130

Heart Rate (bpm)

60 75 90

Normothermia (R2=0.94) Heat Stress (R2=0.92)

Operating Point

Cui, Wilson, Crandall, Am. J. Physiol. Reg Comp. Physiol. 2002

SLIDE 6

Diastolic Blood Pressure (mmHg) 50 55 60 65 70 75 Normalized MSNA (units/beat) 500 1000 1500 2000 2500 3000 Normothermia (R2=0.92) Heat Stress (R2=0.93)

Operating Point

Cui, Wilson, Crandall, Am. J. Physiol. Reg Comp. Physiol. 2002

SLIDE 7

Arterial Baroreflex Testing

Bolus injections of graded concentrations of sodium

nitroprusside (I.V.) induced hypotensive stimuli that activated both aortic and carotid baroreceptors.

Bolus injections of graded concentrations of phenylephrine

(I.V.) induced hypertensive stimuli that activated both aortic and carotid baroreceptors NOTE: Technique characterizes global arterial baroreflex function.

SLIDE 8

Aortic Baroreflex Testing

An appropriate level of neck pressure was applied to

negate phenylephrine induced increases in mean arterial pressure at the carotid sinus preventing activation of carotid baroreceptors.

An appropriate level of neck suction was applied to negate

sodium nitroprusside induced decreases in mean arterial pressure at the carotid sinus preventing activation of carotid baroreceptors. NOTE: Technique isolates aortic baroreflex function

SLIDE 9

Carotid Baroreflex Testing

Method 1 (Built Curves):

– Neck pressure and neck suction applied as 5 sec stimuli – Neck pressure applied to mimic the hypotension induced by systemic administration of sodium nitroprusside – Neck suction applied to mimic the hypertension induced by systemic administration of phenyleprhine

Method 2 (Pulsed Train Curves):

– Neck suction and neck pressure applied as pulsed train stimuli gated to the cardiac cycle R-wave NOTE: Techniques characterize carotid baroreflex function. No differences existed in curve parameters between either method of carotid baroreflex testing.

SLIDE 10

EXAMPLE

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 11

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 12

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 13

SLIDE 14

SLIDE 15

Carotid sinus baroreceptor Aortic baroreceptor

NP NS

Vasodilation Vasoconstriction

Carotid-sinus nerve Aortic nerve

Sympath. cardiac nerves
Sympath. vasoconstrictor nerves

Heart Rate Blood pressure Exercise Pressor Reflex Arterial Pressure

SLIDE 16

SLIDE 17

SLIDE 18

SLIDE 19

Querry et al. AJP 2001

SLIDE 20

MAP or HR Estimated Carotid Sinus Pressure

Saturation Threshold Centering Point (A3) Responding Range (A1) Operating Range Operating Point Minimum Response (A4) Max gain Slope (A2)

Protocol Chamber Pressure (Torr)

100
80
60
40
20

20 40 60

Built Neck Pressure and Suction Reflex Function Curves

Estimated Carotid Sinus Pressure (mmHg)

20 40 60 80 100 120 140 160

HR (bpm)

50 55 60 65 70 75 80

SLIDE 21

NP/NS stimulation

(5s NP/NS protocol) The 5s NP/NS can be used to analyze CBR function during relatively long duration, steady-state conditions. Example- rest, dynamic exercise, heat stress, etc. Advantage- can measure MSNA & blood flow responses, can distinguish latency of cardiac and vasomotor component Limitation- time (rapid NP/NS protocol) The rapid NP/NS can be used to analyze CBR function during relatively short duration, steady-state conditions. Example- static exercise, tilt, LBNP, etc. Advantage- time Limitation- cannot be used during high HR conditions (RRI<stimulation time=500ms)

SLIDE 22

Breath-hold during NP/NS stimulation

(Rest) The NP/NS pulse train was conducted during 10 to 15s breath-hold at end-expiration to minimize the respiratory-related modulation of HR and MAP (Eckberg 1976) (Exercise) During exercise, NP/NS pulse train are applied without the presence of a breath-hold. Eckberg et al.(1980) reported no differences between the responses to neck collar stimuli during inspiration and expiration at a breathing frequency of >24 breaths/min.

SLIDE 23

HR (bpm)

2 3 4 5 6 7 8

T i m e ( s )

024681 1 2

CP (mmHg)

6
4
2

E s t i m a t e d c r a

t

i d s i n u e p r e s s u r e ( m m H g )

2 4 6 8 1 1 2 1 4 1 6

HR (bpm)

3 5 4 4 5 5 5 5 6 6 5 7

Carotid-HR baroreflex Curve The HR responses to NS (-60mmHg) Average of peak values ECSP=MAP-CP

*

SLIDE 24

MAP (mmHg)

4 6 8 1

T i m e ( s )

024681 1 2

CP (mmHg)

6
4
2

E s t i m a t e d c a r

t

i d s i n u s p r e s s u r e ( m m H g )

2 4 6 8 1 1 2 1 4 1 6

MAP (mmHg)

4 5 5 5 5 6 6 5 7 7 5 8

Carotid-MAP baroreflex Curve MAP responses to NS (-60mmHg) Average of peak values ECSP=MAP-CP

*

SLIDE 25

E C S P ( m m H g )

2 4 6 8 1 1 2 1 4 1 6

HR (bpm)

3 5 4 4 5 5 5 5 6 6 5 7

T i m e ( s )

2 4 6 8 1 1 2 1 4 1 6

CP (mmHg)

1
8
6
4
2

2 4 6

HR (bpm)

3 4 5 6 7 8

MAP (mmHg)

5 6 7 8 9

9 beats Carotid-HR baroreflex Curve The HR and MAP responses to rapid changes in NP and NS

Curve calculated from 5 s protocol

9 beats

SLIDE 26

E C S P ( m m H g )

2 4 6 8 1 1 2 1 4 1 6

MAP (mmHg)

4 5 5 5 5 6 6 5 7 7 5 8

T i m e ( s )

2 4 6 8 1 1 2 1 4 1 6

CP (mmHg)

1
8
6
4
2

2 4 6

HR (bpm)

3 4 5 6 7 8

MAP (mmHg)

5 6 7 8 9

9 beats Carotid-MAP baroreflex Curve The HR and MAP responses to rapid changes in NP and NS

Curve calculated from 5 s protocol

9 beats

SLIDE 27

Workload

 Heart rate  Blood pressure

?

SLIDE 28

SLIDE 29

Ex (moderate)

ECSP

Heart Rate Rest Ex (light) OP CP Ex (heavy) Operating Range

Ogoh et al. J Physiol. 2003

SLIDE 30

Potts et al. AJP 1993 Norton et al. JAP 1999

Ex (moderate)

ECSP

Mean Arterial Pressure Rest Ex (light) OP CP Ex (heavy) Operating Range

SLIDE 31

ECSP

Heart Rate

r

Mean Arterial Pressure Rest Exercise OP CP

(Rest) max gain  gain at OP  gain at CP (Exercise) max gain  gain at OP <gain at CP

Relocated OP underestimates max Gain during exercise by using data points around OP!!

SLIDE 32

SLIDE 33

8

0- 4 004 2 4 6 8 1 1 2 1 4 1 6

8

0- 4 004

8
4

004

8
4

004

Neck Chamber Pressure (mmHg)

Rest EX90 EX120 EX150

SV responses to NP/NS during exercise

Stroke Volume (mmL)

20 40 60 80 100

Estimated Carotid Sinus Pressure (mmHg) Chamber Pressure (Torr)

120
80
40

40 80

Ogoh et al. J Physiol. 2003

SLIDE 34

Stroke Volume (mmL)

20 40 60 80 100

Estimated Carotid Sinus Pressure (mmHg) Chamber Pressure (Torr)

120
80
40

40 80

MAP=  HR×  SV×  SVC  MAP=  HR×k×  SVC

Flow Vasomotor Reaction

Time (sec.)

2 4 6 8 10 12

The change of HR or MAP (bpm or mmHg)

5

5 10 15

Cntribution of TPR Contribution of Q HR MAP 5 sec NP (40mmHg)

Ogoh et al. J Physiol. 2002

SLIDE 35

Rest 120EX 50 100

Q TVC

The contribution to changes in arterial blood pressure (%)

SLIDE 36

Central Command CNS Baroreflex Neurons Muscle Chemoreflex Sympathetic Nervous System SNA (BP) (CSP) BP OP

A

SNA (BP) (CSP) BP OP

B

SNA (BP) (CSP) BP OP

A+B

Rowell & O’Leary JAP 1990

SLIDE 37

SLIDE 38

Gallagher et al. J Physiol. 2001

Static Exercise Dynamic Exercise

Carotid Sinus Pressure (mmHg)

SLIDE 39

Gallagher et al. J Physiol. 2001

SLIDE 40

Static exercise

20 40 60 80 100 120 140 160 180 200

Heart Rate (beats/min)

40 50 60 70 80 90 100

Control - Rest Control - Exercise MAST - Exercise

Calculated Carotid Sinus Pressure (mmHg)

20 40 60 80 100 120 140 160 180 200

Mean Arterial Pressure (mmHg)

70 80 90 100 110 120 130

Dynamic exercise

20 40 60 80 100 120 140 160 180 200

Heart Rate (beats/min)

40 50 60 70 80 90 100

Calculated Carotid Sinus Pressure (mmHg)

20 40 60 80 100 120 140 160 180 200

Mean Arterial Pressure (mmHg)

70 80 90 100 110 120 130

Control - Rest Control - Exercise MAST - Exercise

Gallagher et al. J Physiol. 2001

SLIDE 41

SLIDE 42

HR (beat/min)

55 60 65 70 75 80 85

baseline E1 E2 E3 R1 R2 Mean arterial pressure (mmHg)

80 90 100 110 120 130 9 10 11 12 13 14 15

Control extension Vibration

A B C

* * * * * *

50 100 150

HR (beat/min)

50 60 70 80 90

Rest Vibration Extension Estimated carotid sinus pressure (mmHg)

50 100 150

MAP (mmHg)

80 90 100 110 120

Rest Vibration Extension

Knee Extension

*p<0.05 Ogoh et al. J Physiol. 2002

SLIDE 43

9 10 11 12 13 14 15

Control flexion Vibration HR (beat/min)

55 60 65 70 75 80 85

baseline E1 E2 E3 R1 R2 Mean arterial pressure (mmHg)

80 90 100 110 120 A B C

* * * * * * *

Estimated carotid sinus pressure (mmHg)

50 100 150 80 90 100 110 120

Rest Flexion Vibration

Knee Flexion

*p<0.05

50 100 150

HR (bpm/min)

50 60 70 80 90

Rest Flexion Vibration

Ogoh et al. J Physiol. 2002

SLIDE 44

+EPR

EPR

Con-Ex

CC

A.

Con- Ex +EPR

EPR

B.

ECSP ECSP ECSP ECSP OP Heart rate Heart rate Mean arterial pressure Mean arterial pressure

+CC

OP

+CC

OP

CC

OP

Con-Ex Con-Ex

Querry et al. AJP-Heart. 2001 Smith et al. J Physiol. 2003 Gallagher et al. Exp. Physiol. 2006

SLIDE 45

SLIDE 46

V S S+ED

0.0 0.2 0.4 0.6 0.8 1.0 1.2

V S S+ED

5 10 15 20 25 30 35 40

V S S+ED

5 10 15 20

 O2 Cons (l O2/min)  Heart Rate (bpm)  CO (l/min)  Blood Pressure (mmHg)

Strange et al. JP 1993

V S S+ED

5 10 15 20 25

SLIDE 47

Overall Resetting Exercise Pressor Reflex Central Command

ECSP HR or MAP OP

Con Ex

CP

Raven et al. Exp. Physiol. 2006

SLIDE 48

SUMMARY The arterial barorefex is reset by activation of either central command or the exercise pressor reflex.

SLIDE 49

Operating Range Operating Range

CENTRAL COMMAND EXERCISE PRESSOR REFLEX Mechano- and Metabo-receptors Cardiopulmonary Baroreceptors

MAP

SNA NTS PSNA

Afferent Nerve Firing MAP MAP

MAP

Aortic and Carotid Baroreceptors Rest Exercise

Rest Exercise

SNA PSNA

Raven et al. Exp.Physiol.2006

SLIDE 50

SLIDE 51

Fadel et al. Am. J. Physiol., 2001

CBR Control of MSNA at Rest and During Dynamic Exercise

SLIDE 52

CBR-LVC Function Curve

Estimated Carotid Sinus Pressure (mmHg) 40 60 80 100 120 140 160 180 Leg Vascular Conductance (% change)

40
30
20
10

10 20 30

Operating point Centering point

SLIDE 53

Leg Blood Flow (ml/min)

5 1 1 5 2 2 5 3 R E S T N E L E L

Leg Vascular Conductance (ml/mmHg/min)

5 1 1 5 2 2 5 3 R E S T N E L E L

* * † * † *

LVC (ml/min/mmHg)

SLIDE 54

Leg Vascular Conductance (ml/mmHg/min)

6
4
2

2 4 6 +40 Torr

60 Torr

* * † * †

NEL REST EL

* Absolute Change to +40mmHg

increased contribution Rest Exercising Leg increased contribution from Rest

Keller et al., JAP 2003

SLIDE 55

Leg Vascular Conductance (% change)

40
30
20
10

10 20 30 40 +40 Torr

60 Torr

REST NEL EL

* † † * *

* % Change to +40mmHg

reduced vasoconstriction Rest Exercising Leg reduced vasoconstriction from Rest

Keller et al., JAP 2003

SLIDE 56

α1

ET

Gq

PLC PKC DAG PIP2 IP3

Ca2+ VSM contraction

PKC

free bound

MAP kinase

VSM contraction K+

(hyperpolarization)

+

K+

GK

A1 α2

Ca2+ Ca2+

α1 A1

AC ATP cAMP

AT1

DAG

SR

+

ROC/VOC Ca2+ Channels

+

+ +

A2 PC

Gi

Prostacyclin Adenosine Endothelin Angiotensin II NE NE Adenosine

SLIDE 57

Central Command Exercise Pressor Reflex

Arterial Baroreflex

CNS

VSM

Angiotensin II Endothelin Norepinephrine

*constrictors

Adenosine Prostacyclin NO, H+, pCO2, pO2 Epinephrine KATP Channel

*dilators NTS

MSNA

SLIDE 58

Leg Vascular Conductance (% change)

40
35
30
25
20
15
10
5

Rest Exer Exer w/ Glyburide

Percent Change

NP (+40mmHg)

Keller et al., JP 2004

SLIDE 59

Arterial Baroreflex Testing

Bolus injections of graded concentrations of sodium

nitroprusside (I.V.) induced hypotensive stimuli that activated both aortic and carotid baroreceptors.

Bolus injections of graded concentrations of phenylephrine

(I.V.) induced hypertensive stimuli that activated both aortic and carotid baroreceptors NOTE: Technique characterizes global arterial baroreflex function.

SLIDE 60

Aortic Baroreflex Testing

An appropriate level of neck pressure was applied to

negate phenylephrine induced increases in mean arterial pressure at the carotid sinus preventing activation of carotid baroreceptors.

An appropriate level of neck suction was applied to negate

sodium nitroprusside induced decreases in mean arterial pressure at the carotid sinus preventing activation of carotid baroreceptors. NOTE: Technique isolates aortic baroreflex function

SLIDE 61

Carotid Baroreflex Testing

Method 1 (Built Curves):

– Neck pressure and neck suction applied as 5 sec stimuli – Neck pressure applied to mimic the hypotension induced by systemic administration of sodium nitroprusside – Neck suction applied to mimic the hypertension induced by systemic administration of phenyleprhine

Method 2 (Pulsed Train Curves):

– Neck suction and neck pressure applied as pulsed train stimuli gated to the cardiac cycle R-wave NOTE: Techniques characterize carotid baroreflex function. No differences existed in curve parameters between either method of carotid baroreflex testing.

SLIDE 62

EXAMPLE

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 63

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 64

Smith et al., Autonomic Neuroscience (2001), 74-85

SLIDE 65

Valsalva I phase; intra-thoracic pressure ↑ ABP ↑ HR ↓ II phase; venous return ↓ ABP ↓ HR ↑ III phase; intra-thoracic pressure ↓ ABP ↓↓ HR ↑↑ IV phase; venous return ↑↑ ABP ↑↑ (overshoot) HR ↓↓

SLIDE 66

Iellamo et al Am J Physiol 1994

Sequence Technique

SLIDE 67

Iellamo et al Am J Physiol 1994

SLIDE 68

500 1000 1500 2000 80 100 120 140 160

SAP (mmHg) RR (ms)

500 850 1200 80 130 180 SAP R-R INTERVAL

Iellamo et al Am J Physiol 1994

SLIDE 69

200 600 1.000

50 100 150 200 250 300

TIME mmHg

msec mmH g

INCREMENTAL EXERCISE TEST

TIME

Iellamo et al Faseb J 1998

SLIDE 70

MAP or HR

Estimated Carotid Sinus Pressure

Saturation Threshold Centering Point (A3) Responding Range (A1) Operating Range Operating Point Minimum Response (A4) Max gain Slope (A2)

Protocol Chamber Pressure (Torr)

100
80
60
40
20

20 40 60

Built Neck Pressure and Suction Reflex Function Curves

Estimated Carotid Sinus Pressure (mmHg)

20 40 60 80 100 120 140 160

HR (bpm)

50 55 60 65 70 75 80

SLIDE 71

Iellamo et al Faseb J 1998

SLIDE 72

HR vs. RRI

RRI1 HR2 HR1 RRI2

H R ( b p m )

2 4 6 8 1 1 2 1 4 1 6 1 8 2 2 2

RRI (ms)

2 4 6 8 1 1 2 1 4 1 6 1 8 2 2 2

RRI1/HR1> RRI2/ HR2 500/20 > 50/20

SLIDE 73

RRI (msec)

2 4 6 8 1 1 2

E C S P ( m m H g )

4 6 8 1 1 2 1 4 1 6

Gain (msec/mmHg)

5 1

HR (bpm)

4 6 8 1 1 2 1 4 1 6 1 8

E C S P ( m m H g )

4 6 8 1 1 2 1 4 1 6

Gain (bpm/mmHg)

1

.

.

5 .

HR RRI

Heavy Ex Moderate EX Mild Ex Rest

Ogoh et al. J Physiol. 2003

SLIDE 74

1) Neck pressure and suction technique

CBR CP CSP input HR ∆CSP = -CP ∆HR

utput

CBR sensitivity = ∆HR/∆CSP ABP variability HR variability ABR CP Resp. input

utput

Cardiovascular centers Reflex modulation

2) Transfer function analysis

HF LF

Frequency Power Frequency Power

ABR sensitivity = Transfer function gain = SHR·ABP(f)/SMAP·MAP(f)

SLIDE 75

0.0 0.1 0.2 0.3 0.4

Transfer function gain (bpm/mmHg)

1 2 3 4 Rest EX120 Rest EX90 EX120 EX150

Transfer function gain (bpm/mmHg)

1 2 3 LF HF *† *† *† *†

Rest EX90 EX120 EX150 ECSP (mmHg) 50 100 150 HR (beats/min) 60 80 100 120 140 160

Centering Point Threshold Saturation Operating Point

NP/NS protocol Transfer function analysis

SLIDE 76

MAP or HR

Estimated Carotid Sinus Pressure

Saturation Threshold Centering Point (A3) Responding Range (A1) Operating Range Operating Point Minimum Response (A4) Max gain Slope (A2)

Protocol Chamber Pressure (Torr)

100
80
60
40
20

20 40 60

Built Neck Pressure and Suction Reflex Function Curves

Estimated Carotid Sinus Pressure (mmHg)

20 40 60 80 100 120 140 160

HR (bpm)

50 55 60 65 70 75 80

SLIDE 77

Contribution of cardiac output (Q) and total vascular conductance (TVC) to the carotid baroreflex-mediated changes in MAP at the time

f peak HR and peak MAP at rest and during mild (EX90), moderate

(EX120) and heavy (EX150) exercise

* P<0.05 vs. rest, $ P<0.05 vs. EX90

a t t h e t i m e

f

p e a k H R

R e s t E X 9 0 E X 1 2 0 E X 1 5

% Contribution

2
1

1 2 3 Q T V C

a t t h e t i m e

f

p e a k M A P

R e s t E X 9 0 E X 1 2 0 E X 1 5

% Contribution

4
2

2 4 6 8 1 1 2 1 4 0 Q T V C

* * * *$ * * * * *$ * * *

Ogoh et al. J Physiol. 2003

SLIDE 78

NP/NS method Max gain and OP gain during dynamic exercise with metoprolol and glycopyrrolate

Control

Rest EX90 EX120 EX150 GMAX or GOP (bpm/mmHg)

0.6
0.5
0.4
0.3
0.2
0.1

0.0 GMAX GOP

Metoprolol

Rest EX90 EX120 EX150

Glycopyrrolate

Rest EX90 EX120 EX150

#

*†‡ *† * *† *†

# # # # # # $ $ $& $& $

Ogoh et al. 2005 JP (Accepted)

SLIDE 79

R e s t E X 9 E X 1 2 E X 1 5 LF GTF between HR and MAP (bpm/mmHg)

0.0 0.5 1.0 1.5

Control Metoprolol Glycopyrrolate

R e s t E X 9 E X 1 2 E X 1 5

LF GTF between HR and SBP (bpm/mmHg)

0.0 0.5 1.0 1.5

*†‡ *† * * *† *†

# # #$ # # #

*†‡ *† * * *† *†

# # #$ # # #

RRI/MAP

Rest EX90 EX120 EX150 SBR (ms/mmHg)

10 20 30 40 50

Control Metoprolol Glycopyrrolate

RRI/SBP

Rest EX90 EX120 EX150 SBR (ms/mmHg)

10 20 30 40

* * * *

#$ #

* * * * *

# #

*

# #

*† *†

Transfer function analysis Sequence technique

Ogoh et al. 2005 JP (Accepted)

SLIDE 80

SUMMARY

The sensitivity of the cardiac-arterial baroreflex
btained from the two dynamic methods is similar

to the operating point gain obtained from logistic modeling of the HR responses to the carotid baroreceptor stimulation using a variable pressure neck collar.

In the transition from rest to exercise the
perating point of the HR baroreflex was relocated

to regulate the prevailing arterial pressure with a sensitivity less than its maximal sensitivity.

The relocation of the operating and the reduction

in the range of HR response was a result of the vagal withdrawal associated with increasing exercise intensity.

SLIDE 81

Operating Range Operating Range

CENTRAL COMMAND EXERCISE PRESSOR REFLEX Mechano- and Metabo-receptors Cardiopulmonary Baroreceptors

MAP

SNA NTS PSNA

Afferent Nerve Firing MAP MAP

MAP

Aortic and Carotid Baroreceptors Rest Exercise

Rest Exercise

SNA PSNA

Raven et al. Exp.Physiol.2006

SLIDE 82

Operating Range Operating Range

CENTRAL COMMAND EXERCISE PRESSOR REFLEX Mechano- and Metabo-receptors Cardiopulmonary Baroreceptors

MAP

SNA NTS PSNA

Afferent Nerve Firing MAP MAP

MAP

Aortic and Carotid Baroreceptors Rest Exercise

Rest Exercise

SNA PSNA Raven et al., 2006

SLIDE 83

Operating Range Operating Range

CENTRAL COMMAND EXERCISE PRESSOR REFLEX Mechano- and Metabo-receptors Cardiopulmonary Baroreceptors

MAP

SNA NTS PSNA

Afferent Nerve Firing MAP MAP

MAP

Aortic and Carotid Baroreceptors Rest Exercise

Rest Exercise

SNA PSNA Raven et al., 2006