Tyramine-induced endogenous noradrenaline efflux from in situ cardiac sympathetic nerve ending in cats

The full text article is temporarily unavailable.

We apologise for the inconvenience. Please try again later.

Download / Buy Article:

Abstract:

With the use of dialysis technique, the effects of tyramine on in situ cardiac sympathetic nerve endings were examined in anaesthetized cats. Dialysis probes were implanted in the left ventricular myocardium, and the concentration of dialysate noradrenaline (NA) served as an indicator of NA output at the cardiac sympathetic nerve ending. Locally applied tyramine (600 μM) increased dialysate NA levels from 17 ± 1 (pg mL-1) to 3466 ± 209 (pg mL-1). Pretreatment with reserpine (vesicle transport NA blocker 1 μM) did not affect tyramine-induced NA efflux. The tyramine-induced NA efflux was augmented by pretreatment with pargyline (1 mM) but suppressed by pargyline (10 mM). Pretreatment with α-methyl-tyrosine suppressed NA efflux evoked by tyramine. These pretreatments did not affect the time course of NA efflux but only altered peak height of NA efflux. The efflux of NA evoked by tyramine was not associated with any reduction of dihydroxyphenylglycol (DHPG). In contrast, in the pretreatment with reserpine, the efflux of NA was associated with a reduction of DHPG. This result suggests that NA graduation between axoplasm and stored vesicle contributes to maintaining the axoplasmic NA level during carrier-mediated outward NA transport. The tyramine-induced NA efflux provides a close reflection of the NA content at the nerve ending. With the use of dialysis, this experimental model is suitable for studying the mechanism of sympathomimetic amine-induced neurotransmitter efflux.

Keywords: carrier-mediated outward transport; methyl-para-tyrosine; microdialysis; pargyline; reserpine; sympathomimetic amine

Document Type: Research Article

Affiliations: Department of Cardiac Physiology, National Cardiovascular Center Research Institute, Suita, Osaka, Japan

Publication date: February 1, 2000

Related content

Tools

Favourites

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more