[The two faces of veno-arteriolar reflex: cutaneous vasodilatation and vasoconstriction to raise and to lower the arm].
BACKGROUND
The veno-arteriolar reflex (VAR) is triggered by an increase in the transmural venous pressure on placing a part of the body in the same direction as the gravitational acceleration below the heart.


OBJECTIVE
To assess the VAR in healthy subjects on raising a part of the body above the level of the heart.


METHODS
VAR was studied in 16 healthy subjects (20-65 years old) by means of changes in the blood flow in the skin detected using a digital infrared photoplethysmograph attached to the fingertip under the following conditions: right arm at the height of the heart, right arm below the heart and right arm below the level of the heart. The variables measured were: amplitude of the blood flow in the skin with the arm raised to the height of the heart (baseline amplitude), percentage decrease of the blood flow in the skin with the arm below the heart and percentage increase in blood flow with the arm above the heart.


RESULTS
The percentage of vasoconstriction with the right arm below the heart was 35%, and that of vasodilation, 50%.


CONCLUSIONS
Evaluation of the VAR with the arm below the heart causes vasoconstriction, and elevation of the arm causes an important degree of vasodilation. Vasoconstriction and vasodilation are maintained while the limb is kept above or below the heart. This is an economical and potentially very useful way of studying the innervation of the microcirculation in a number of different peripheral neuropathies of thin and mixed fibres.
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
B
B
Estanol-Vidal
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
F
F
Gutierrez-Manjarrez
Instituto Nacional de Cardiologia Ignacio Chavez, Tlalpan, Mexico.
R
R
Martinez-Memije
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
H
H
Senties-Madrid
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
M J
MJ
Berenguer-Sanchez
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
L
L
Magana-Zamora
Hospital Universitario de la Universidad Autonoma de Nuevo Leon (UANL), Monterrey, Mexico.
G
G
Delgado-Garcia
Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Tlalpan, Mexico.
E
E
Chiquete-Anaya
D000328:Adult; D000368:Aged; D001132:Arm / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D012018:Reflex; D012039:Regional Blood Flow; D012867:Skin; D014661:Vasoconstriction; D014664:Vasodilation; D055815:Young Adult