An investigation was made into some of the hemodynamic properties of
bone. The parameters studied were bone marrow and medullary venous
pressures. The resting level and changes in the two pressures were measured
under autoperfusion and constant-flow perfusion conditions. Changes were
induced either by drugs or by alteration in blood flow. Marrow pressure was
measured with a new tonometric technique. A specially constructed miniature
pressure transducer was utilized as the tonometer. Trauma-induced
hemorrhage of the marrow was avoided. The marrow pressure was measured
across an intact endosteal membrane. The pressure of the normal bone marrow
and the medullary venous pressure in the anesthetized dog were nearly
equal, approximately twenty millimeters of mercury and about 17 per cent of
systemic blood pressure. These values were found whether measured
simultaneously or separately in comparable groups of dogs under a variety
of conditions. Induced changes in the two pressures produced either by
changes in perfusion rate or by drugs were also nearly equal and in the
same direction.