In vitro reactivity of dog cavernous carotid artery to stretch and adrenergic stimulation.
The reactivity of the dog cavernous carotid artery to stretch, field electrical stimulation, and norepinephrine was studied using arterial segments under isometric conditions. Light microscopy revealed that this artery is of muscular type and its external surface is covered by venous endothelium, and fluorescence microscopy showed a dense adrenergic innervation. On stretch, arteries exhibited an immediate, transient contraction (phasic response) and a late, maintained contraction (tonic response) that were unaffected by tetrodotoxin (10(-6) M) or endothelium removal but were reduced by the inhibitors of cyclooxygenase indomethacin (10(-6) M), acetylsalicylic acid (3 x 10(-5) M), or meclofenamate (10(-5) M). Electrical stimulation (0.5-4 Hz) contracted the arteries in a frequency-dependent manner, and the response was reduced by tetrodotoxin, phentolamine, (10(-6) M), or the inhibitors of cyclooxygenase used but was unaffected by endothelium removal. Norepinephrine (10(-9)-3 x 10(-4) M) caused dose-dependent contraction that was blocked by phentolamine and by the inhibitors of cyclooxygenase but was not modified by endothelium removal. The results indicate that the dog cavernous carotid artery develops myogenic tone on stretch and contracts on adrenergic stimulation. They also suggest that in these responses prostaglandins but not the endothelium are involved. Therefore, the cavernous carotid artery, because of its location and reactivity, could be of relevance in regulating blood flow or pressure within the cerebral circulation when arterial pressure or adrenergic activity increases.
Valle
J
J
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain.
García-Villalón
A L
AL
Nava-Hernández
E
E
García
J L
JL
Santamaría
L
L
Gómez
B
B
Diéguez
G
G
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D002343:Carotid Artery, Internal / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D004285:Dogs; D004558:Electric Stimulation; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008469:Meclofenamic Acid / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D012701:Serotonin; D013779:Tetrodotoxin; D008469:Meclofenamic Acid; D000109:Acetylcholine; D001241:Aspirin; D009638:Norepinephrine; D007213:Indomethacin; D010646:Phentolamine