[Ca²⁺] changes in sympathetic varicosities and Schwann cells in rat mesenteric arteries—Relation to noradrenaline release and contraction

Abstract

Aim:This study aimed to assess intracellular Ca 2+ dynamics in nerve cells and Schwann cells in isolated rat resistance arteries and determine how these dynamics modify noradrenaline release from the nerves and consequent force development. Methods: Ca 2+ in nerves was assessed with confocal imaging, noradrenaline release with amperometry and artery tone with wire myography. Ca 2+ in axons was assessed after loading with Oregon Green 488 BAPTA-1 dextran. In other experiments, arteries were incubated with Calcium Green-1-AM which loads both axons and Schwann cells. Results: Schwann cells but not axons responded with a Ca 2+ increase to ATP.Electrical field stimulation of nerves caused a frequency-dependent increase in varicose [Ca 2+ ] ([Ca 2+ ] v ). ω-conotoxin-GVIA (100 nmol/L) reduced the [Ca 2+ ] v transient to 2 and 16 Hz by 60% and 27%, respectively; in contrast ω-conotoxin GVIA inhibited more than 80% of the noradrenaline release and force development at 2 and 16 Hz. The K V channel blocker, 4-aminopyridine (10 µmol/L), increased [Ca 2+ ] v , noradrenaline release and force development both in the absence and presence of ωconotoxin-GVIA. Yohimbine (1 µmol/L) increased both [Ca 2+ ] v and noradrenaline release but reduced force development. Acetylcholine (10 µmol/L) caused atropinesensitive inhibition of [Ca 2+ ] v , noradrenaline release and force. In the presence of ω-conotoxin-GVIA, acetylcholine caused a further inhibition of all parameters. Conclusion: Modification of [Ca 2+ ] in arterial sympathetic axons and Schwann cells was assessed separately. K V 3.1 channels may be important regulators of [Ca 2+ ] v , noradrenaline release and force development. Presynaptic adrenoceptor and muscarinic receptor activation modify transmitter release through modification of [Ca 2+ ] v . K E Y W O R D S amperometry, confocal imaging, neurotransmission, prejunctional modulation, small arteries, sympathetic 2 of 11 | HANSEN Et Al.

Reduce, replace, refine—Animal experiments

“…These are still used in physiological research and deliver excellent research results. [7][8][9][10] These technologies should be preserved for the future. Some techniques are performed in only one or two groups around the world and the knowledge and skills how they are performed might be forgotten in the near future.…”

Curses or Cures: A Review of the Numerous Benefits Versus the Biosecurity Concerns of Conotoxin Research

“…Voltage-sensitive binding/blocking of voltage-gated K-channels [15] Cancer [93], cardioprotection in ischemia [94] κM-RIIIJ Voltage-gated K + channels Subtype selectivity [95,96] Neuronal profiling [5,6,97,98], channel subtype expression profiling [96,99] ω-GVIA Voltage-gated Ca 2+ channels Subtype selective [37,99] Neurotransmission [100][101][102], pain [103], cardiology [55], epilepsy [104], renal function [105], nuclear signaling [106] ω-MVIIC Voltage-gated Ca 2+ channels Inhibits various subtypes broadly [107,108] Epilepsy [109], long-term depression [110], pain [111,112]…”

Dynamic monitoring of single-terminal norepinephrine transporter rate in the rodent cardiovascular system: A novel fluorescence imaging method

“…Rodent cardiac chambers (LAA, left atrial appendage; RAA, right atrial appendage; LV, left ventricle; RV, right ventricle) and mesenteric arteries (MA) were dissected free as described (Holmes et al, 2016;Hansen et al, 2019), transferred to the imaging chamber and securely pinned down as flat as possible onto a Sylgard-lined base. Tissues were continuously superfused at 2 ml·min −1 with warmed (35-37°C), oxygenated KH solution for at least 20 min prior to ex vivo studies.…”