Single capillary studies at California Institute of Technology indicate that intravascular pressure, not metabolic need, governs blood flow at the local level, investigators say.
The work was done with cats by Paul C. Johnson, PhD, associate professor of physiology, Indiana University School of Medicine, and Harold Wayland, PhD, professor of engineering science, CIT.
They developed a technique for measuring flow velocity of erythrocytes in single capillaries. Dr. Johnson told JAMAMedical News that it involves a microscope with mercury arc light source, and a projection system to display the microcirculation on an adjacent screen.Noting that this area of investigation dates back to the pioneer Dutch microscopist Anton van Leeuwenhoek, Dr. Johnson said:"From these studies, we know that blood flow velocity in systemic capillaries is of the order of 1 mm per second. However, it also is known from direct observation that flow in single capillaries is