Local electric stimulation causes conducted calcium response in rat interlobular arteries
AJP - Renal Physiology
Rathlou. Local electric stimulation causes conducted calcium response in rat interlobular arteries. Am J Physiol The purpose of the present study was to investigate the conducted Ca 2ϩ response to local electrical stimulation in isolated rat interlobular arteries. Interlobular arteries were isolated from young Sprague-Dawley rats, loaded with fura 2, and attached to pipettes in a chamber on an inverted microscope. Local electrical pulse stimulation (200 ms, 100 V) was administered by means of
... NaCl-filled microelectrode (0.7-1 M⍀) juxtaposed to one end of the vessel. Intracellular Ca 2ϩ concentration ([Ca 2ϩ ]i) was measured with an image system at a site ϳ500 m from the location of the electrode. The expression of mRNA for pore-forming units Ca V3.1 and CaV3.2 of voltagesensitive T-type channels was investigated by using RT-PCR. Current stimulation elicited a conducted [Ca 2ϩ ]i response. A positive electrode (relative to ground) increased [Ca 2ϩ ]i to 145 Ϯ 7% of baseline, whereas the response was absent when the electrode was negative. This response was not dependent on perivascular nerves, because the conducted response was unaffected by TTX (1 M). The conducted [Ca 2ϩ ]i response was abolished by an ambient Ca 2ϩ free solution and blunted by nifedipine (1 M). Rat interlobular arteries exhibited conducted [Ca 2ϩ ]i response to current stimulation. This response was dependent on Ca 2ϩ entry. L-type Ca 2ϩ channels may play a role in this process.