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CA-45(2+) MOVEMENTS INDUCED BY CA2+ CHLORIDE IN ISOLATED RAT AORTA UNDER K+-FREE CONDITIONS

WERMELSKIRCHEN, D., NEBEL, U., WIRTH, A. & WILFFERT, B., 17-Jan-1991, In : European Journal of Pharmacology. 192, 3, p. 403-408 6 p.

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Increasing the extracellular Ca2+ concentration induced a dihydropyridine-insensitive contraction in the isolated rat aorta bathed in K+-free solution. To obtain further insight into the mechanism of this contraction Ca-45(2+) uptake measurements were carried out with isolated rat aorta. Increasing the extracellular Ca2+ concentration from 0.63 to 5.0 mM enhanced the Ca-45(2+) uptake from 186 +/- 3 to 359 +/- 12 dpm/mg ww (n = 8). Under K+-free conditions increasing the extracellular Ca2+ concentration from 0.63 to 5.0 mM enhanced the Ca-45(2+) uptake from 184 +/- 4 to 541 +/- 6 dpm/mg ww (n = 12) and elicited an increase in tension of 10.0 +/- 0.4 mN (n = 9). The Ca2+-induced Ca-45(2+) uptake was not affected by the Ca2+ channel antagonists, nifedipine (L-type), flunarizine (L- and T-type) and omega-conotoxin (N-type). Amiloride, a blocker of the Na+/Ca2+ exchange, indomethacin, a blocker of prostaglandin synthesis, the local anaesthetic, lidocaine, and the Ca2+ overload blocker, R 56865, had no effect on Ca2+-induced Ca-45(2+) uptake. Additionally, R 56865 did not affect the Ca2+-induced contractile response. The inorganic Ca2+ entry blocker, lanthanum, reduced both the non-stimulated and stimulated Ca-45(2+) uptake and inhibited the Ca2+-induced contractile response. We would like to suggest that the Ca-45(2+) uptake induced by Ca2+ under K+-free conditions enters the cell via the leakage Ca2+ channel, because lanthanum was an effective antagonist and a significant contribution of any other Ca2+ pathway could not be demonstrated.

Original languageEnglish
Pages (from-to)403-408
Number of pages6
JournalEuropean Journal of Pharmacology
Volume192
Issue number3
Publication statusPublished - 17-Jan-1991

    Keywords

  • CA-45(2+) UPTAKE, CA2+ CHANNELS (LEAKAGE), AORTA (RAT), CA2+ ENTRY BLOCKERS, VASCULAR SMOOTH-MUSCLE, CONTRACTILE RESPONSES, HYPERTENSIVE RATS, CALCIUM CHANNELS, OUABAIN, TRANSPORT, CELLS, EXCHANGE

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