Abstract
Complete absence of magnesium has a two-fold effect on the arterial tone: direct smooth muscle contraction and relaxation via endothelium-derived relaxing factor (EDRF) release. In the present study performed on a systemic vein we investigated (1) which of these effects dominates following reduction of magnesium concentration from 1.2 mM to 0.8 and 0.4 mM and (2) whether the vessel segments asymmetrically respond when the magnesium concentration is reduced on either the intra- or extraluminal side. The effects of reducing magnesium concentration on both the isometric tension of isolated ring preparations and the diameter of isolated, perfused and superfused feline femoral veins were investigated. In nor-adrenaline-precontracted rings, rapid decreases in the extracellular magnesium concentration from 1.2 mM to 0.8 and 0.4 mM caused relaxation, whereas total omission of magnesium returned the tone to the level of the initial tone induced by noradrenaline. Both in the presence of haemoglobin (5×10−6M), and in vessels without endothelium, lowering the magnesium concentration caused a dose-dependent elevation of the noradrenaline-induced tone. In perfused and superfused noradrenaline-contracted vein segments, each reduction of extraluminal magnesium concentration caused contraction of the vessels, regardless of whether the endothelium was intact or not. A decrease in intraluminal magnesium concentration did not alter the diameter of the vessel when the endothelium was intact, but caused contraction when the endothelium was disrupted. The results of the present study demonstrate that both the reduction of magnesium concentration or its complete absence cause an EDRF-mediated relaxation and a directly mediated smooth muscle contraction in the femoral vein of the cat. Within the physiological range of extracellular magnesium concentrations, however, the EDRF-mediated relaxation seems to dominate.
Similar content being viewed by others
References
Altura BM, Altura BT (1981) Magnesium ions and contraction of vascular smooth muscles: relationship to some vascular diseases. Fed Proc 40:2672–2679
Cohen RA, Shepherd JT, Vanhoutte PM (1984) Endothelium and asymmetrical responses of the coronary arterial wall. Am J Physiol 247:H403-H408
Cooper KE (1981) Functional aspects of the venous system. In: Schwartz CJ, Werthessen NT, Wolf S (eds) Structure and function of the circulation, vol 2. Plenum, New York, pp 457–485
De Mey JG, Vanhoutte PM (1982) Heterogenous behaviour of the canine arterial and venous wall. Circ Res 51:439–447
Faragó M, Szabó C, Dóra E, Horváth I, Kovách AGB (1991) Contractile and endothelium-dependent dilatory responses of cerebral arteries at various extracellular magnesium concentrations. J Cereb Blood Flow Metab 11:161–164
Furchgott RF, Zawadzki JV (1980) The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine. Nature 288:373–376
Gold ME, Buga GM, Wood KS, Byrns RE, Chaudhuri G, Ignarro LJ (1990) Antagonistic modulatory roles of magnesium and calcium on release of endothelium-derived relaxing factor and smooth muscle tone. Circ Res 66:355–366
Högestatt ED, Andersson KE, Edvinsson L (1983) Mechanical properties of rat cerebral arteries as studied by a sensitive device for recording of mechanical activity in isolated small blood vessels. Acta Physiol Scand 117:49–61
Ignarro LJ (1989) Biological actions and properties of endothelium-derived nitric oxide formed and released from artery and vein. Circ Res 65:1–21
Komori K, Lorenz RR, Vanhoutte PM (1988) Nitric oxide, ACh and electrical and mechanical properties of canine arterial smooth muscle. Am J Physiol 255:H207-H212
Ku DD, Ann HS (1987) Magnesium deficiency produces endothelium-dependent vasorelaxation in canine coronary arteries. J Pharmacol Exp Ther 241:961–966
Lew MJ, Rivers RJ, Duling BR (1989) Arteriolar smooth muscle responses are modulated by an intramural diffusion barrier. Am J Physiol 257:H10-H16
Ljung B (1969) Local transmitter concentrations in vascular smooth muscle during vasoconstrictor nerve activity. Acta Physiol Scand 77:212–223
Long CJ, Stone TW (1985) The release of endothelium-derived relaxing factor is calcium dependent. Blood Vessels 22:205–208
Lopez-Jaramillo P, Gonzalez MC, Palmer RMJ, Moncada S (1990) The crucial role of physiological Ca2+ concentrations in the production of endothelial nitric oxide and the control of vascular tone. Br J Pharmacol 101:489–493
Martin W, Villani GM, Jothianandan D, Furchgott RF (1985) Selective blockade of endothelium-dependent and glyceryl trinitrateinduced relaxation by hemoglobin and by methylene blue in the rabbit aorta. J Pharmacol Exp Ther 232:708–716
Miller RC, Vanhoutte PM (1989) Is nitric oxide the only endothelium-derived relaxing factor in canine femoral veins? Am J Physiol 257:H1910-H1916
Monos E (1990) Magnesium und glatte Muskulatur. In: Weidinger H (ed) Medizin, Management, Magnesium. Blackwell Ueberreuter, Berlin, pp 262–271
Murgo JP, Cox RH, Peterson LH (1971) Cantilever transducer for continuous measurement of arterial diameter in vivo. J Appl Physiol 31:948–953
Rubanyi GM, Vanhoutte PM (1988) Heterogenity of endothelium-dependent responses to acetylcholine in canine femoral arteries and veins. Blood Vessels 25:75–81
Rude RK, Singer FR (1981) Magnesium deficiency and excess. Annu Rev Med 32:245–259
Sercombe R, Hardebo JE, Kahrström J, Seylaz J (1990) Amine-induced responses of pial and penetrating cerebral arteries: evidence for heterogeneous responses. J Cereb Blood Flow Metab 10:808–818
Szabó C, Faragó M, Dóra E, Horváth I, Kovách AGB (1991) Endothelium-dependent influence of small changes in extracellular magnesium concentration on the tone of feline middle cerebral arteries. Stroke 22:785–789
Vanhoutte PM, Janssens WJ (1978) Local control of venous function. Microvasc Res 16:196–214
Verrecchia C, Sercombe R, Philipson V, Seylaz J (1986) Functional destruction of cerebral vascular endothelium by Triton X-100. Blood Vessels 23:106 (abstract)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Szabó, C., Bérczi, V., Schneider, F. et al. Role of endothelium in the response of the vein wall to magnesium withdrawal. Pflügers Arch. 420, 140–145 (1992). https://doi.org/10.1007/BF00374982
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00374982