Cat cerebral arterial smooth muscle cells express cytochrome P450 4A2 enzyme and produce the vasoconstrictor 20-HETE which enhances L-type Ca2+ current

• Published in: The Journal of physiology 1998-03, Vol.507 (3), p.771-781
• Main Authors: Gebremedhin, Debebe, Lange, Andrew R., Narayanan, Jayashree, Aebly, Mikael R., Jacobs, Elizabeth R., Harder, David R.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Arachidonic Acid - metabolism; Cats; Cerebral Arteries - metabolism; Cerebral Arteries - physiology; Cloning, Molecular; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System - biosynthesis; Cytochrome P-450 Enzyme System - chemistry; DNA Primers; Humans; Hydroxyeicosatetraenoic Acids - metabolism; Hydroxyeicosatetraenoic Acids - pharmacology; In Vitro Techniques; Membrane Potentials - drug effects; Membrane Potentials - physiology; Mixed Function Oxygenases - biosynthesis; Mixed Function Oxygenases - chemistry; Molecular Sequence Data; Muscle, Smooth, Vascular - metabolism; Muscle, Smooth, Vascular - physiology; Nifedipine - pharmacology; Original; Polymerase Chain Reaction; Rats; RNA, Messenger - biosynthesis; Sequence Alignment; Sequence Homology, Amino Acid; Transcription, Genetic; Vasoconstriction - drug effects; Vasoconstriction - physiology; Vasoconstrictor Agents - pharmacology
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1111/j.1469-7793.1998.771bs.x

Cerebral arteries express cytochrome P450 4A enzymes (P450 4A) and produce 20- hydroxyeicosatetraenoic acid (20-HETE), a potent constrictor of pial arterioles. It is not known which cell type in the vessel wall is responsible for the formation of 20-HETE. We examined whether freshly isolated cerebral arterial muscle cells (VSMCs) express P450 4A and produce 20-HETE. We also studied the effect of 20-HETE on pressurized cerebral arteries and on whole-cell L-type Ca 2+ current ( I Ca ) recorded in cat cerebral VSMCs. Cat cerebral VSMCs incubated with [ 14 C]arachidonic acid ([ 14 C]AA) produced 20-HETE (3.9 ± 1.1 pmol min −1 (mg protein) −1 ). Reverse transcription-polymerase chain reaction studies revealed that cat cerebral VSMCs express mRNA for P450 4A which metabolizes AA to 20-HETE. Cloning and sequencing of the cDNA amplified from mRNA isolated from VSMCs showed > 96% amino acid homology to the rat and human P450 4A2 and 4A3. 20-HETE (1–300 n m ) induced a concentration-dependent constriction of cat cerebral arteries, which was inhibited by nifedipine. Addition of 10 and 100 n m 20-HETE to the bath increased peak I Ca by 50 ± 3 and 100 ± 10%, respectively. This effect was not influenced by altering the frequency of depolarization. 20-HETE (100 n m ) failed to increase I Ca in the presence of nifedipine. These results demonstrate that cat cerebral VSMCs express P450 4A enzyme, and produce 20-HETE which activates L-type Ca 2+ channel current to promote cerebral vasoconstriction.