Stochastic aspects of leukocyte transit in hamster cheek pouch arterioles.

To clarify the dynamics of leukocyte delivery to the capillary network we measured leukocyte velocity (Vwbc), leukocyte flux and the intra-arrival times between successive leukocytes in terminal arterioles of the cheekpouch of eight hamsters. The sequences, generated electronically when fluorescent leukocytes passed a fixed point in the arteriole, were analyzed as stochastic point processes. Results showed that six sequences were stationary, and two with a linear trend in Vwbc, were not. Tests performed on the stationary sequences indicated conformity to a renewal process in all cases. Analysis of the distributional and sequential properties of the sequences indicated a good fit to a Poisson process. Overall these results show that leukocyte delivery to the capillary network can be characterized as a Poisson process if Vwbc remains relatively constant, if not, a non-homogeneous Poisson process is a more suitable model, with Vwbc being the explanatory variable. The demonstration of the applicability of these models may lead to a more complete understanding of both the physiological and patho-physiological dynamics of leukocytes within the microvasculature.