Intraarterial protamine sulfate reduces the magnitude of streaming potentials in living canine tibia

Using previously described techniques, transcortical streaming potentials were measured at two middiaphyseal sites on one tibia of each of nine anesthetized canines during sinusoidal bending (approximately 0 to -200 mu epsilon periosteal surface strain) at 2 Hz. Measurements were made for 60 minutes prior to and up to 180 minutes following bolus injection of protamine sulfate (42-126 mg/kg) dissolved in Hanks Balanced Salt Solution, directly into the femoral artery without interrupting circulation. Shortly after injection, the protamine sulfate caused a clear reduction in the magnitude of streaming potentials. Subsequent injections of additional protamine sulfate resulted in further reductions, and in several instances, voltage sign reversals. This study represents the first observation that circulating proteins may alter electromechanical transduction in living bone, and suggests the possibility that specific agents, which are known to affect bone remodeling, may do so, in part, by altering these endogenous electrical potentials.