Among other parameters, varying blood flow values may be responsible for
tumor-to-
tumor variabilities in the radiobiologically hypoxic cell fraction of experimental rodent
tumors. To test whether changes in
tumor blood flow may be caused by
anesthetic agents often used in radiobiology, the effect of
injectable and inhalational
anesthetics and of
neuroleptic, neuroleptanalgesic, and
sedative agents on blood flow in subcutaneous DS-
carcinosarcomas implanted in Sprague-Dawley rats has been investigated using the 85Kr clearance technique. In conscious rats, 20-100 min after animal instrumentation mean blood flow is 0.62 +/- 0.17 ml/g/min (mean +/- SD) in 0.75 +/- 0.15 g
tumors at a mean arterial blood pressure of 125 +/- 12 mm Hg. In animals receiving
thiobutabarbital,
chloral hydrate, or
methoxyflurane tumor blood flow is somewhat higher than that measured in conscious rats.
Tumor blood flow in animals receiving
etomidate,
ketamine-
xylazine,
fentanyl-
fluanisone, or
urethane is significantly lower than that in the
thiobutabarbital group and somewhat lower than in the conscious animals. Blood flow values observed with
midazolam,
ketamine-
midazolam,
fentanyl-droperidol,
droperidol,
diazepam, and
pentobarbital are similar to those measured in conscious rats. Virtually no flow alterations with time are detectable in conscious rats and with most of the drugs used. In animals anesthetized with
urethane or
methoxyflurane,
tumor blood flow increases and
tumor vascular resistance diminishes slightly with time.