The Effects of Diuretics on Intracellular Ca2+ Dynamics of Arteriole Smooth Muscles as Revealed by Laser Confocal Microscopy

• Tamagawa Yasunori

  Department of Anatomy (Cell Biology), School of Medicine, Iwate Medical University

• Saino Tomoyuki

  Department of Anatomy (Cell Biology), School of Medicine, Iwate Medical University

• Matsuura Makoto

  Department of Advanced Pharmaceutics, School of Pharmacy, Iwate Medical University

• Satoh Yoh-ichi

  Department of Anatomy (Cell Biology), School of Medicine, Iwate Medical University

Abstract

The regulation of cytosolic Ca²⁺ homeostasis is essential for cells, including vascular smooth muscle cells. Arterial tone, which underlies the maintenance of peripheral resistance in the circulation, is a major contributor to the control of blood pressure. Diuretics may regulate intracellular Ca²⁺ concentration ([Ca²⁺]_i) and have an effect on vascular tone. In order to investigate the influence of diuretics on peripheral resistance in circulation, we investigated the alteration of [Ca²⁺]_i in testicular arterioles with respect to several categories of diuretics using real-time confocal laser scanning microscopy. In this study, hydrochlorothiazide (100 μM) and furosemide (100 μM) had no effect on the [Ca²⁺]_i dynamics. However, when spironolactone (300 μM) was applied, the [Ca²⁺]_i of smooth muscles increased. The response was considerably inhibited under either extracellular Ca²⁺-free conditions, the presence of Gd³⁺, or with a treatment of diltiazem. After the thapsigargin-induced depletion of internal Ca²⁺ store, the spironolactone-induced [Ca²⁺]_i dynamics was slightly inhibited. Therefore, the spironolactone-induced dynamics of [Ca²⁺]_i can be caused by either a Ca²⁺ influx from extracellular fluid or Ca²⁺ mobilization from internal Ca²⁺ store, with the former being dominant. As tetraethylammonium, an inhibitor of the K⁺ channel, slightly inhibited the spironolactone-induced [Ca²⁺]_i dynamics, the K⁺ channel might play a minor role in those dynamics. Tetrodotoxin, a neurotoxic Na⁺ channel blocker, had no effect, therefore the spironolactone-induced dynamics is a direct effect to smooth muscles, rather than an indirect effect via vessel nerves.<br>

Journal

• ACTA HISTOCHEMICA ET CYTOCHEMICA

  ACTA HISTOCHEMICA ET CYTOCHEMICA 42 (4), 121-128, 2009

  JAPAN SOCIETY OF HISTOCHEMISTRY AND CYTOCHEMISTRY

Keywords

• confocal microscopy
• diuretics
• intracellular calcium ion
• testicular arterioles

Details

• CRID: 1390282679840147712
• NII Article ID: 130000118210
• DOI: 10.1267/ahc.09006
• ISSN: 13475800
• ISSN: 00445991
• Web Site: http://www.jstage.jst.go.jp/article/ahc/42/4/42_09006/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/2010127308
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed