Effects of bradykinin on [3H]-norepinephrine release in rat hypothalamus.
1. We examined the regulatory actions of bradykinin on norepinephrine release in the hypothalamus of rats. 2. Bradykinin increased the stimulation-evoked [3H]-norepinephrine release from hypothalamic slices of Sprague-Dawley rats in a dose-dependent manner (1 Hz: S2/S1 ratio, mean +/- s.e.m., control 0.868 +/- 0.016, n = 6; bradykinin 1 x 10(-6) mol/L 1.039 +/- 0.018, n = 6, P < 0.05; bradykinin 3.3 x 10(-6) mol/L 1.130 +/- 0.064, n = 6, P < 0.05). The basal release of [3H]-norepinephrine was not affected by the peptide. 3. Bay K 8644, a dihydropyridine-sensitive calcium channel agonist, significantly potentiated the facilitatory effect of bradykinin on norepinephrine release, although Bay K 8644 by itself had no significant effect. By contrast, nicardipine, a dihydropyridine-sensitive calcium channel blocker, reversed the increase in norepinephrine release induced by bradykinin and Bay K 8644. 4. These results indicate that bradykinin may increase norepinephrine release in rat hypothalamus, partially mediated by interactions with dihydropyridine-sensitive calcium channels.
Tsuda
K
K
Neurochemistry Research Laboratories, New York University Medical Center, New York, New York.
Tsuda
S
S
Goldstein
M
M
Nishio
I
I
Masuyama
Y
Y
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology* / Q000502:physiology; D002490:Central Nervous System / Q000502:physiology; D004347:Drug Interactions; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D009529:Nicardipine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D009435:Synaptic Transmission / Q000502:physiology; D014316:Tritium
D014316:Tritium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009529:Nicardipine; D001920:Bradykinin; D009638:Norepinephrine