[Effect of the injection of cyclosporine A on the peripheral venous resistance in dogs].

We have studied the effect of cyclosporin on the peripheral venous system. CSA was injected into an isolated hind limb saphenous vein perfused at constant flow in 29 dogs. Reactivity of the vein was tested with infusions of norepinephrine (NE) before and after CSA. In a 1st group of 7 dogs, CSA at doses of 5, 10 and 20 mg was infused over a 10-minute period. In a 2nd group of 8 dogs, 20 mg of CSA was infused over 20 minutes and, injections of 6, 12 and 24 micrograms of NE were administered before and during CSA. In a 3rd (n = 7) and 4th (n = 7) groups of animals, 30 mg of CSA was injected over 60 minutes and injections of 3, 6, 12 micrograms of NE were given before and during CSA. In the last group, an ipsilateral lumbar sympathectomy was performed before CSA injection. The infusion of CSA over periods of 10 and 20 minutes did not cause significant changes in venous perfusion pressure. The infusion of 30 mg of CSA over 60 minutes caused an increase in venous perfusion pressure from 44 +/- 2 mm Hg to 58 +/- 5 mm Hg (p < 0.0001). Surgical sympathectomy prevented the venoconstrictor response to CSA. Injections of 3, 6 and 12 +/- g of NE caused averaged increases of 25 +/- 6, 39 +/- 9 and 53 +/- 10 mm Hg before CSA, and of 45 +/- 7, 69 +/- 12 and 84 +/- 8 mm Hg respectively after CSA injections, a significant increase (p = 0.03). In conclusion, CSA causes a vasoconstriction of the saphenous vein through stimulation of the sympathetic nervous system and potentiates the venoconstrictor effect of NE.