Contrasting actions of cocaine, local anaesthetic and tetrodotoxin on discharge properties of rat aortic baroreceptors

Michael Andresen, M. Brodwick, M. Yang

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

1. Effects of cocaine, lignocaine, benzocaine and tetrodotoxin (TTX) on the simultaneously measured pressure- and diameter-discharge frequency relations of single fibre baroreceptors were compared in rat in vitro aortic arch-aortic nerve preparations. 2. Between 1 and 10 μM, cocaine produced selective increases in the pressure threshold shifting the pressure-response curve without altering the gain or threshold frequency. At near-blocking concentrations, gain was depressed as well. Cocaine experiments were done in nitroprusside (NP, 1 μM). Neither NP or NP with cocaine altered diameter (P > 0.36). 3. Lignocaine (at > 10 μM) and benzocaine (at > 100 μM) shifted pressure-response curves to higher pressures and generally depressed discharge by increasing pressure threshold and decreasing maximum discharge frequency (P <0.05). Gain decreased and threshold frequency increased at higher concentrations. Diameter was unaffected by lignocaine or benzocaine (P > 0.14). 4. TTX increased thresholds and discharge frequencies at threshold but did not shift pressure-discharge curve locations. This produced superimposable discharge curves with changes occurring as losses of discharge points in the threshold region. Diameter was unaffected by TTX (P > 0.80). 5. The contrasting patterns of effects between TTX and local anaesthetics suggest that blockade of TTX-sensitive sodium channels alone may not be responsible for the effects of cocaine, lignocaine and benzocaine.

Original languageEnglish (US)
Pages (from-to)309-319
Number of pages11
JournalJournal of Physiology
Volume477
Issue number2
StatePublished - 1994

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Pressoreceptors
Tetrodotoxin
Local Anesthetics
Cocaine
Pressure
Benzocaine
Lidocaine
Sodium Channels
Nitroprusside
Thoracic Aorta

ASJC Scopus subject areas

  • Physiology

Cite this

Contrasting actions of cocaine, local anaesthetic and tetrodotoxin on discharge properties of rat aortic baroreceptors. / Andresen, Michael; Brodwick, M.; Yang, M.

In: Journal of Physiology, Vol. 477, No. 2, 1994, p. 309-319.

Research output: Contribution to journalArticle

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