Effect of chronic administration of Cecropia obtusifolia (Moraceae)

COMUNICACIONES
Rev. Biol. Trop., 35(2): 359-362, 1 987.
Effect of chronic administration of Cecropia obtusifolia (Moraceae)
on mean arterial pressure in rats
Isaías G . Salas· , Orlando M . Morales" , J .R. Brenes"
•
Depto. de Farmacología. Escuela de Medicina, Universidad de Costa Rica.
.. Depto. de Fisiología, Escuela de Medicina, Universidad de Costa Rica.
(Received December 1 9 , 1 986)
Resumen Se le administró un extracto acuoso liofilizado de la morácea Cecropia obtusifolia en el agua de beber a un
grupo de ratas (hembras y machos) de la variedad de hipertensas espontáneas.
En 10$ machos no se encontraron diferencias 5ignificativas en la presión arterial media y en la frecuencia cardiaca al
cabo de cuatro semanas de ingerir el extracto. En el caso de las hembras sólo se detectaron diferencias significativas
en la presión arterial media, al término de la cu arta semana, pero no en la frecuencia cardíaca.
Aqueous leaf extracts of Cecropia obtusifo­
lia have been shown to have a hypotensive
effect when given intravenously in nonnal rats
(Vidrio 1 982) and dogs (Salas 1 985), but the
mean arterial pressure feIl deeper and with last­
ing effect on conscious spontaneousIy hyper­
tensive rats, SHR (Salas et al. , 1986). There­
fore , it seemed interesting to test the extract on
the SHR model when the extract is given chron­
icaIly per os.
The experiment was carried out using two
groups, male (n = 20) and female (n = 1 5) ma­
ture SHR. Treated animals drank an aqueous
solution of the extract in the drinking water
(fmal concentration of 20 mgjkg) and the con­
trol received tap water, in both cases ad libio
tumo The rats were housed in groups of three or
six animals and fed with a rat chow (La Pradera
S.A.) purchased from a local supplier. At flXed
week1y periods, a group of animals (5 to 7) was
prepared for mean arterial pressure recording.
Under ether anesthesia a carotid artery was
catheterized with polyethilene tubing (PE-50)
in the morning, and late in the same aftemoon
the MAP was measured in a conscious state , by
means of a strain gauge transducer and a Hew­
lett Packard polygraph (model 7754 A). Caro
diac frequency was detennined from the pulse
wave of the pressure recording.
Measurements of the cardiovascular parame­
ters of the males were obtained at the end of
the fust, third and fourth weeks; and in fe­
males, at the end of the third and fourth weeks.
In both cases, changes in the cardiovascular pa­
rameters were statiscally compared with control
animals by means of a "t" test for independent
groups.
The aqueous leaf extract given to SHR ad
libitum did not show any significant differences
in both MAP and cardiac frequency, when com­
pared with the controls, in the tested weeks (1,
III and IV) (Figs. 1 and 2). Even though the
experimental female group followed the same
trend , at the end of the fourth week the MAP
was lower than the control (p< 0.05) (Fig. 2).
Because the ingestion of the drinking water
and the extract did not differ among them on a
per weight basis, a different amount of the ac­
tive principie could not explain this finding,
which probably is due to sex characteristics.
REFERENCES
Salas, I .G . 1 98 5 . Mecanismo de acción cardiovascular
de los extractos frescos liofilizados de Cecropia
obtusifolia, Bertol. Tesis de Maestría, Universidad
de Costa Rica, San José, Costa Rica.
359
360
REVISTA DE BIOLOGIA TROPICAL
�
1>1
f
�
Q)
?;
--
1=1
f
�
'1J
Q)
3:
1-..J
O
o::
�
z
O
ü
�
--
I�I
+
.>O:
Q)
Q)
?;
.
t--
1=1
+
.x
<l.I
<l.I
3:
.-
1-1
I
I
.>O:
<l.I
Q)
3:
--
..J
O
cr.
í-Z
O
ü
+
I
O
O
�
I
O
lO
r()
I
O
C\J
r()
T
O
<Xl
C\J
I
O
�
C\J
I
O
O
C\J
I
O
lO
beats / min
I
O
C\J
I
O
<Xl
I
O
�
O
Fig. 1 Effect of chronic administration of C. obtusifolia on cardiac frecuency in consciou s spontaneously hypertensive
rats ( SHR).
SALAS et al. .' Effect of Cecropia on arterial pressure
36 1
1--
I�
+
"""
<1>
<1>
3:
f--
1=1
I
I
�
<1>
<1>
0+
�
---.J
+
-
O
o::
fZ
O
U
f--
I�!
+
�
<1>
<1>
�
-
f--
1=1
+
�
<1>
<1>
�
f--
1 -1
+
-"
<1>
<1>
3:
--
.....J
O
o::
�z
O
U
+
I
O
ro
I
O
L()
I
O
(\J
I
O
(J)
I
O
<.D
MAP m m Hg
I
O
r<>
O
Fig. 2 Effect of chronic administration of e oftusifolia on mean arterial pressure in consciou s spontaneously
hypertensive rats (SHR).
362
REVISTA DE BIOLOGIA TROPICAL
Salas, I .G ., 1 . R. Brenes & Orlando Morales. 1 9 86 .
Antihypertensiye effeet of a C. obtusifolia leaf ex­
traet on conscious spontaneously hypertensiye rats.
Rey. Biol. Trop . (in press) .
Vidrio, H. 1 982. Hypotensiye aetivity of CecropÚJ
obtusifolia. 1 . Pharm . Sei. 7 1 : 475-476 .