162 Determination of Capsaicin Induced Increase in Dermal Blood Flow Using Laser Doppler Flowmetry Technique
significantly increased dermal blood flow as compared to
placebo. Van der Schueren et al., have demonstrated the
increase in blood flow after application of 300 and 1000
micro grams of capsaicin while the application of 100
micro grams didn’t produce any increase in blood flow
[23].
In our study the blood flow measurement was carried-
out after 30 minutes application of capsaicin. It has been
shown that 1000 micrograms of capsaicin produced the
maximum response between 30 and 45 minutes after
application and at 60 minutes time point there was de-
crease in blood flow [23]. There was increase in blood
flow (291 ± 85.3 %) with 0.075% capsaicin application
compared to placebo in our study. Helme and McKernan
have extensively investigated the wide variation in size
and intensity of capsaicin induced flare response [7].
According to these authors, site of application and age
were the factors responsible for large variation. Gazerani
et al. recently found that capsaicin induced sensory and
vasomoto r responses were also g ender specific [24 ]. The
present study was conducted only in male gender. Het-
erogeneity in th e density an d function of capsaicin sensi-
tive nociceptive nerve endings of the dermal microcircu-
lation seem to be the most plausible explanation. There
may be variation in the response due to difference be-
tween the proximal and distal forearm, due to difference
in skin thickness [23]. We have thus applied the capsai-
cin 10 cms distal to elbow crease to avoid this site varia-
tion.
Munce and Kenney reported decrease in local skin
blood flow response in older participants than healthy
males [25]. Age had a significant effect on local vasodi-
lation with younger individuals having percentage of
maximal cutaneous vascular conductance (% CVCmax) at
least 2 times greater than seen in older group. Previous
observations of decrease flare size in older individuals
after acute application of capsaicin suggest that there is
reduction in reduced skin blood flow in these subjects [7].
We included only younger individuals, the average age
of participants in our study was 27.8 ± 3.9 yrs. Acute
capsaicin stimulates a specific population of sensory
nerves in the skin that possess capsaicin receptors, elic-
iting local release of vasoactive neurotransmitters from
their nerve endings [25]. The further use of our model
can have advantage in dose finding and proof of concept
studies.
5. Conclusions
The present study has shown an increase in the dermal
blood flow induced by topical application capsaicin on
the human forearm using laser Doppler flowmetry tech-
nique. Hence, this pharmacodynamic model which is non-
invasive, technically uncomplicated and sound, might
therefore facilitate the early evaluation of antagonists of
mediators involved in neurogenic inflammation, includ-
ing CGRP, TRPV1 and possibly, SP antagonists in hu-
mans.
6. Acknowledgements
The study was funded through the Indian Council of
Medical Research (ICMR) fund, Government of India.
The authors declare no financial conflict of interest con-
nected to this study and its results.
We thank the Director, Nizam’s institute for provid-
ing us the necessary infrastructure.
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