Regional differences in skin blood flow as measured by radioactive microspheres

Regional skin blood flows in the trunk were measured by means of radioactive labeled microspheres in anesthetized rats and monkeys. Mean arterial pressure, heart rate, cardiac output and arterial pH, pO2 and pCO2 were registered and body and ambient air temperature were kept constant for the duration of the experiments. The blood flows were determined on a total of 6 skin samples, 2 samples each from the thoracic, lumbar and sacral regions. The reproducibility of the microsphere technique for measurements were given with a 10 min interval. The coefficient of variation varied with the region from 10.3 to 22.7%. In both species the skin blood flows in the thoracic regions were significantly higher than in the lumbar and sacral regions (P less than 0.05). The skin blood flows in the thoracic region of the rat ranged from 39-45 ml.min-1.100 g-1, in the lumbar region from 32-33 and in the sacral region from 29-30. In the monkeys the corresponding values for the different regions were: thoracic: 7-9, lumbar 5-7 and sacral: 4-7 ml.min-1.100 g-1, respectively. Our results support the use of radioactive microspheres for skin blood flow measurements, and demonstrate the existence of regional differences in the skin blood flow of the trunk. We suggest that this may be an important consideration during the development, and interpretation of data from experimental models in which skin blood flow is important.