Gc. Jiang et al., THE DIFFERENCE IN NIFEDIPINE SENSITIVITY BETWEEN HYPERTENSIVE AND NORMOTENSIVE RAT AORTAE IS DEPENDENT ON AGE, Clinical and experimental pharmacology and physiology, 22(1), 1995, pp. 17-20
1. In order to investigate further whether the increased sensitivity t
o inhibition by nifedipine of the responses to noradrenaline of aortae
from spontaneously hypertensive stroke-prone (SHRSP) rats is related
to the development of the hypertension, we have compared the sensitivi
ty to noradrenaline, potassium chloride (KCI) and nifedipine of aortae
from SHRSP and control (Wistar-Kyoto) WKY rats of different age group
s (young: 3-5 weeks, and adult: 13-16 weeks). 2. The sensitivity to KC
l was found to be less in the aortae from the adult WKY group than in
any of the other three groups, Responses to noradrenaline of the adult
WKY aortae were also less sensitive to inhibition by nifedipine in co
mparison to each of the other three groups. 3. The changes in sensitiv
ity were not due to the changes in the populations of alpha(1)-adrenoc
eptor subtypes as responses of the adult SHRSP aortae to noradrenaline
were more sensitive to nifedipine in the presence of either the alpha
(1)-adrenoceptor subtype antagonists chloroethylclonidine or WB4101 th
an were those of the adult WKY aortae, but aortae from the young SHRSP
were not. 4. These results suggest that, rather than the SHRSP aorta
becoming more sensitive to nifedipine and potassium depolarization as
hypertension develops, if is the WKY aorta that becomes more resistant
as it matures.