Active Ion Transport Across Canine Blood Vessel Walls

Abstract

Experiments giving evidence of active Na and C1 ion fluxes across large canine blood vessel walls (aorta, vena cava) in vitro have been presented. The information has been obtained using ion tracer techniques after Ussing and with diffusion cells of the Hogben type. The available data suggest that the membranes are satisfactorily oxygenated by the bathing solutions saturated with oxygen at atmospheric pressure. Evidence is offered which indicates that active ion transport does occur across the aorta and vena cava in in vitro experiments. Under the conditions of the experiment net Na and C1 flux takes place from intima to adventitia across the aorta, and from adventitia to intima across the vena cava at low measured potential differences. The possible relationships of derangement of active ion transport mechanisms, produced by electric currents and tissue injury potential differences, to intravascular thrombosis are alluded to. It would appear that sodium and chloride fluxes across large blood vessel walls in vitro occur at least in part as the result of metabolic processes and cannot be explained simply on the basis of diffusion across a semipermeable membrane.Applied electrical fields and those created by currents of injury in injured tissues appear related to intravascular occlusion of blood vessels (1-3). Abramson, Gorin, and Ponder (4), Furchgott and Ponder (5), Ponder apd Ponder (6), and others have indicated that the cellular elements of blood at a pH of 7.40 move toward the positive pole in an electrophoretic cell. Vascular occlusion can be potentiated in normal vessels by application of a positive electrode (7,8). Occlusion is delayed in an injured blood vessel exposed to the field about a cathode (9, 10). Therefore it is postulated that potential differences in the physiologic range and related currents of injury in perivascular tissues may act as causal agents in intravascular occlusion, by means of their electrophoretic or other effects upon the cellular and possibly liquid elements of the contained blood.As a corollary, it is reasonable to hypothesize that the blood vessel wall

Electroosmotic Characteristics of Canine Aorta and Vena Cava Wall

“…The finding that modified Krebs solution produces greater net water transport per unit current under the conditions of the experiment (Tables II, III, and IV) is in agreement with previous findings by Sawyer and coinvestigators that Na+ (diameter of hydration sphere approximately 2.5 A) (32) and CL-ions traverse the blood vessel wall far more freely than either Ca++ or K+ (8)(9)(10)28). Because of the larger hydration sphere around Ca++ (hydration sphere diameter approximately 7 A) and Mg++ ions contained in Krebs solution, it is possible that more water molecules will be transported per coulomb of current flow when large numbers of divalent ions are present in solution.…”

Electrical Potential Difference Across Blood Vessels

“…The first question which arises is whether the tissues were adequately oxygenated to allow normal metabolism. This has been discussed elsewhere, 4 3 O 2 / min./cm.-at 37 C, and A equals weight) X mg. wet tissue r. X wet weight/dry weight and wet weight/dry weight ratio is 5.0 for the artery. 7 The maximum qO?…”

“…Recently, in a series of several hundred experiments, small net ion fluxes of Na + and Cl~ have been reported across a. canine aorta and vena cava. 4 Heretofore, demonstration of a net ion flux across a membrane has been accompanied by a potential difference across that membrane. The net ion fluxes measured by Sawyer et al 4 should give a potential difference across the membrane of about 50 mv.…”

“…4 Heretofore, demonstration of a net ion flux across a membrane has been accompanied by a potential difference across that membrane. The net ion fluxes measured by Sawyer et al 4 should give a potential difference across the membrane of about 50 mv. This would have been easily detected by our potentionietric technique, and the fact that it was not means that, despite the differential flux, the Cl~ ion activity on both sides of the membrane tends to remain the same.…”

Experimental Observations on Antithrombotic Biophysical Phenomena in Normal and Atherosclerotic Human Aorta and Porcine Aortic Grafts*

“…and charge.1s-21 (4) Active ion transport across the interface, due to either exchange diffusion or energy using enzyme systems. 21 ( 5 ) Electric conductance as measured during the electroosmosis and in the streaming-potential experiments.17 (6) Pressure electroosmosis : ion and water transport across pores due to the effect of pressure exerted across the aortic wall and smaller arteries. This mechanism uses energy provided by the heart pump as a source of ion filtration.18JR*22 (7) Measurement of streaming potentials1' produced by the combined effect of these mechanisms on the blood-intimal interface.…”