Local electric stimulation causes conducted calcium response in rat interlobular arteries.
The purpose of the present study was to investigate the conducted Ca(2+) 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 an NaCl-filled microelectrode (0.7-1 M(Omega)) juxtaposed to one end of the vessel. Intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured with an image system at a site approximately 500 microm from the location of the electrode. The expression of mRNA for pore-forming units Ca(V)3.1 and Ca(V)3.2 of voltage-sensitive T-type channels was investigated by using RT-PCR. Current stimulation elicited a conducted [Ca(2+)](i) response. A positive electrode (relative to ground) increased [Ca(2+)](i) to 145 +/- 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 microM). The conducted [Ca(2+)](i) response was abolished by an ambient Ca(2+) free solution and blunted by nifedipine (1 microM). Rat interlobular arteries exhibited conducted [Ca(2+)](i) response to current stimulation. This response was dependent on Ca(2+) entry. L-type Ca(2+) channels may play a role in this process.
Salomonsson
Max
M
Division of Renal and Cardiovascular Research, Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark. maxsalomon@mfi.ku.dk
Gustafsson
Finn
F
Andreasen
Ditte
D
Jensen
Boye L
BL
Holstein-Rathlou
Niels-Henrik
NH
D000818:Animals; D001158:Arteries / Q000378:metabolism*; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology; D020746:Calcium Channels, L-Type / Q000502:physiology; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000502:physiology; D004553:Electric Conductivity; D004558:Electric Stimulation; D020748:Mibefradil / Q000008:administration & dosage / Q000494:pharmacology; D008839:Microelectrodes; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013779:Tetrodotoxin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D012333:RNA, Messenger; D020748:Mibefradil; D013779:Tetrodotoxin; D002118:Calcium