M. Kahonen et al., COMPARISON OF CUMULATIVE AND NON-CUMULATIVE ADMINISTRATION OF VASOACTIVE AGENTS IN ARTERIAL SMOOTH-MUSCLE RESPONSES IN-VITRO, Pharmacology & toxicology, 73(3), 1993, pp. 142-145
Two methods of determining concentration-response curves were compared
in isolated endothelium-intact mesenteric arterial rings from Wistar
rats: arterial contractile and relaxation responses were elicited by a
dding compounds cumulatively or introducing a single concentration at
a time (non-cumulative method). The contractile responses induced by h
igh concentrations of K+ (20-125 mM) were comparable between the two m
ethods, whether or not the responses were elicited in the presence of
phentolamine (10 muM) and atenolol (10 muM). Noradrenaline (1 nM - 10
muM) likewise induced similar contractions regardless of method of adm
inistration, the only exception being the highest concentration (100 m
uM) which produced lower contractile force when added directly upon re
sting tension than after cumulative administration. This difference wa
s abolished by atenolol (10 muM). Arterial smooth muscle relaxations i
nduced by endothelium-dependent (acetylcholine 1 nM - 10 muM) and -ind
ependent agents (nitroprusside 1 nM - 1 muM, isoprenaline 10 nM - 100
muM) were similar whether the relaxants were added in a cumulative fas
hion or in a single concentration introduced upon each precontraction.
Thus, cumulative and non-cumulative administration of contractile and
relaxing agents give quite comparable results. We conclude that the c
umulative method is a reliable and time-saving way of studying vascula
r smooth muscle responses in vitro.