Unusual pattern of ß-phenylethylamine deamination in the rat heart

• Type: Article in International Scientific Journal
• Date: 2000

Authors

tiago guimaraes, j (Author) FMUP; soares-da-silva, p (Author) FMUP

Journal

Title: Neurobiology

Vol. 8

Pages: 109-118

ISSN: 1216-8068

Publisher: Akademiai Kiado

Indexing

ISI Web of Knowledge

Scopus - 2 Citations

Other information

Authenticus ID: P-007-91R

Abstract (EN): The present study was aimed to determine type A and B MAO activities in rat heart and renal cortex homogenates and evaluate the sensitivity of deamination of 3H-5-HT and 14C-ß-PEA to selective MAO-A and MAO-B inhibitors, respectively Ro 41-1049 and lazabemide. Deamination of ß-PEA in the rat heart was not affected (V(max) = 53±10 vs 42±6 nmol mg protein-1 h-1) by lazabemide (250 nM), but was significantly reduced (V(max) = 10±1 nmol mg protein-1 h-1) by Ro 41-1049 (250 nM). Deamination of ß-PEA in the rat heart is a low affinity process (when compared with that in the kidney) with high K(m) values (244±98 vs 18.6±5.8 ¿M). On the other hand, deamination of 5-HT in the rat heart and renal cortex revealed high K(m) values, which were similar to those for ß-PEA in the heart. Deamination of ß-PEA (1000 ¿M) in the rat heart was inhibited in a concentration-dependent manner by Ro 41-1049 with a K(i) value of 32 nM (22, 48; 95% confidence limits), but not by the selective MAO-B inhibitor lazabemide (up to 500 nM). Inhibition of 5-HT (1000 ¿M) deamination in the rat heart by Ro 41-1049 was also a concentration-dependent process with a K(i) value of 21 (16, 26) nM. Deamination of 5-HT (1000 ¿M) in the rat renal cortex, was inhibited in a concentration-dependent manner by Ro 41-1049 with a K(i) value of 12 (8, 17) nM. Deamination of ß-PEA in the renal cortex was inhibited by lazabemide with a K(i) of 5 (3, 7) nM. In the rat heart, in contrast to that in the renal cortex, the specific MAO-B substrate ß-PEA is deaminated by a form of MAO which most probably corresponds to MAO-A.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10