Non-adrenergic sympathetic vasoconstriction in the eye and some other facial tissues in the rabbit.
The effects of unilateral sympathetic nerve stimulation (SNS) on regional blood flow in the rabbit were studied with radioactive microspheres. SNS at 10 or 4 Hz caused an approximately 60% reduction in choroidal blood flow, which was partly resistant to alpha-adrenoceptor blockade with phenoxybenzamine. The vasoconstriction evoked by SNS at 2 Hz was completely abolished by alpha-adrenoceptor blockade. A similar response was seen in the iris, ciliary body, masseter muscle and lacrimal gland. In the harderian gland, however, SNS (2 Hz) after alpha-adrenoceptor blockade caused a significant reduction in blood flow. In the salivary glands, combined beta- and alpha-adrenoceptor blockade with propranolol and phenoxybenzamine revealed a slight non-adrenergic vasoconstriction during SNS at 10 Hz; however, the blood flow was significantly increased during SNS at 4 and 2 Hz following alpha-adrenoceptor blockade. These results indicate that there is a frequency-dependent, non-adrenergic component in the sympathetic vasoconstriction of the eye and several facial tissues. In the salivary glands, beta-adrenoceptor-mediated vasodilatation tends to mask a non-adrenergic vasoconstriction.
Granstam
E
E
Department of Physiology and Medical Biophysics, University of Uppsala, Sweden.
Nilsson
S F
SF
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002829:Choroid / Q000098:blood supply; D002924:Ciliary Body / Q000098:blood supply; D004558:Electric Stimulation; D005123:Eye / Q000098:blood supply*; D005145:Face / Q000098:blood supply*; D005260:Female; D006243:Harderian Gland / Q000098:blood supply; D007498:Iris / Q000098:blood supply; D007765:Lacrimal Apparatus / Q000098:blood supply; D008297:Male; D008406:Masseter Muscle / Q000098:blood supply; D011817:Rabbits; D012469:Salivary Glands / Q000098:blood supply; D013564:Sympathetic Nervous System / Q000187:drug effects; D014602:Uvea / Q000098:blood supply; D014661:Vasoconstriction
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists