Calcium channel blocker and calmodulin antagonists affect the gradient of free calcium ions in lily pollen tubes

Eur J Cell Biol. 1991 Dec;56(2):319-27.


The distribution of intracellular free calcium ions ([Ca2+]i) was measured in pollen tubes of Lilium longiflorum using video imaging microscopy and the calcium sensitive indicators fura-2 and quin-2. The mean [Ca2+]i in growing pollen tubes measured with fura-2 shows a maximum of 1.7 to 2.6 microM in the tube tip and decreases almost exponentially to 60 to 100 nM at 100 microns behind the tip. Using quin-2, the maximum [Ca2+]i was also found in the tube tip but with a lower Ca2+ concentration, namely 1 microM. Addition of the calcium channel blocker La3+ caused a decrease of the [Ca2+]i maximum in the tube tip, indicating a heterogeneous distribution of Ca2+ channels along the plasma membrane of pollen tubes. The [Ca2+]i increased after addition of vanadate or compound 48/80. This suggests an involvement of a calmodulin-dependent Ca2+ pump in generation of the Ca2+ gradient in lily pollen tubes. The high [Ca2+]i found in the tube tip with fura-2 seems to indicate the real Ca2+ concentration and is probably responsible for vesicle fusion, fragmentation of actin filaments, and inhibition of cytoplasmic streaming.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoquinolines / metabolism
  • Calcium / metabolism*
  • Calcium Channel Blockers / pharmacology*
  • Calmodulin / antagonists & inhibitors*
  • Cell Polarity / drug effects
  • Cell Polarity / physiology*
  • Fluorescent Dyes / metabolism
  • Fura-2 / metabolism
  • Image Processing, Computer-Assisted
  • Lanthanum / pharmacology
  • Pollen / drug effects
  • Pollen / metabolism*
  • Vanadates / pharmacology
  • p-Methoxy-N-methylphenethylamine / pharmacology


  • Aminoquinolines
  • Calcium Channel Blockers
  • Calmodulin
  • Fluorescent Dyes
  • Vanadates
  • p-Methoxy-N-methylphenethylamine
  • Lanthanum
  • Quin2
  • Calcium
  • Fura-2