The role of voltage-dependent calcium channels in angiotensin-stimulated glomerulosa cells

Endocr Res. 1996 Nov;22(4):569-76. doi: 10.1080/07435809609043748.

Abstract

The concept that voltage-dependent Ca2+ influx is essential in the aldosterone stimulating action of angiotensin II (AII) has been recently challenged by the demonstration of the dihydropyridine (DHP) insensitive 'capacitative' Ca2+ uptake mechanism. The DHP-sensitivity of AII-induced aldosterone secretion is still to be explained. In rat glomerulosa cells the lag phase of AII-induced depolarization is more than 30 s, and there is no enhanced Ca2+ influx within the first min of stimulation. Yet we observed that DHPs as well as diltiazem influenced also the peak of cytoplasmic Ca2+ signal, although the peak (approximately 12 s) is attributed to Ca2+ release alone. Nifedipine reduced the Ca2+ transient induced by AII even after complete inhibition of Ca2+ channel activity. Recalling the loose attachment of InsP3 receptors (IP3R) to the plasma membrane, and the homology between the cytosolic domain of IP3R and the Ca2+ release channel (ryanodine receptor) of skeletal muscle, we proposed that DHP-sensitive L-type Ca2+ channels (DHP receptors) influence InsP3-induced Ca2+ release rather than Ca2+ influx in AII-stimulated cells. Although the dominant isoform is the neuroendocrine (D) one, the skeletal muscle isoform of L-type voltage-dependent Ca2+ channel is also expressed in rat glomerulosa cells. This isoform may be a candidate for protein-protein interaction between DHPR and subplasmalemmal IP3R, similarly to that occurring between DHP receptors and ryanodine receptors in skeletal muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology*
  • Animals
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / metabolism
  • Calcium Channels / physiology*
  • Calcium Channels, L-Type
  • Calcium Radioisotopes
  • Cytoplasm / metabolism
  • Dihydropyridines / pharmacology
  • Diltiazem / pharmacology
  • Electrophysiology
  • Inositol 1,4,5-Trisphosphate Receptors
  • Manganese / metabolism
  • Membrane Potentials / drug effects
  • Potassium / pharmacology
  • Rats
  • Rats, Wistar
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Zona Glomerulosa / physiology*

Substances

  • Calcium Channel Blockers
  • Calcium Channels
  • Calcium Channels, L-Type
  • Calcium Radioisotopes
  • Dihydropyridines
  • Inositol 1,4,5-Trisphosphate Receptors
  • Receptors, Cytoplasmic and Nuclear
  • Angiotensin II
  • Manganese
  • 1,4-dihydropyridine
  • Diltiazem
  • Potassium
  • Calcium