Biaxial and failure properties of passive rat middle cerebral arteries

Rodents are commonly used as test subjects in research on traumatic brain injury and stroke. However, study of rat cerebral vessel properties has largely been limited to pressure-diameter response within the physiological loading range. A more complete, multiaxial description is needed to guide experiments on rats and to appropriately translate findings to humans. Accordingly, we dissected seven rat middle cerebral arteries (MCAs) and subjected them to combined inflation and axial stretch tests around physiological loading conditions while in a passive state. The MCAs were finally stretched axially to failure. Responses in the axial and circumferential directions were relatively similar in contrast to previously reported behavior of human cerebral arteries. Failure stretch values were similar in rat and human vessels, but corresponding stress values for rats were considerably lower than those for humans. Differences between human and rat vessel properties should be considered in rat models of human cerebrovascular injury and disease.