techniques of handling were indistinguishable in terms of blood pressure
and heart rate increase they induce.
Under stressful conditions of open field test cardiovascular parameters
in mice were elevated and there was little difference, if any, between
heart rate at rest and during trotting at 8 m/min. HR values in
this test are very close to the physiological maximum as the administration
of cholinolytic ipratropium bromide cannot increase HR further
compared to control trials. HR increase obviously results from sympathetic
activation and can be greatly diminished with the adrenoblocker
atenolol. When mice were treated with diazepam to reduce
anxiety, their HR was lower particularly at rest.
In treadmill test mice ran at speeds of 6, 12 and 18 m/min. Over this
range of speeds some HR increase was found, however its amplitude
was roughly 1/7–1/10 of HR increase observed after simply placing
the mice on the treadmill (to which they had already been accustomed
for several consecutive days). Pharmacological interventions revealed