title: Perivascular blood attenuates noradrenergic but not cholinergic effects on piglet pial arterioles.
abstract: We examined the chronic and acute effects of perivascular blood on cerebrovascular responses to norepinephrine and acetylcholine in 35 piglets. In the chronic experiment, fresh autologous blood (n = 15) or cerebrospinal fluid (n = 14, control) was placed under the dura mater over the parietal cortex, and the piglets were allowed to recover from anesthesia. One to 4 days later, a closed cranial window was placed over the parietal cortex and baseline pial arteriolar responses and responses to topical application of the neurotransmitters norepinephrine (10(-6) and 10(-4) M) and acetylcholine (10(-4) M) were determined. We also sampled cerebrospinal fluid from under the window during baseline conditions and during application of the neurotransmitters, and we measured the concentrations of prostanoids (6-ketoprostaglandin F1 alpha, thromboxane B2, prostaglandin F2 alpha, and prostaglandin E2) via radioimmunoassay. Pial arterioles in the chronic control group (n = 13) constricted by 20 +/- 2% (mean +/- SEM) in response to 10(-4) M norepinephrine and by 28 +/- 2% in response to 10(-4) M acetylcholine. In the chronic blood group (n = 14), pial arterioles did not constrict significantly in response to 10(-4) M norepinephrine but constricted normally (23 +/- 4%) in response to 10(-4) M acetylcholine. In the acute experiment, six other piglets had blood placed on the brain surface for 30 minutes and then removed; pial arterioles constricted by 21 +/- 1% in response to 10(-4) M norepinephrine (n = 5) and by 28 +/- 4% in response to 10(-4) M acetylcholine (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
authors.forename: D W
authors.initials: DW
authors.lastname: Busija
authors.forename: C W
authors.initials: CW
authors.lastname: Leffler
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001160:Arterioles / Q000187:drug effects; D001790:Blood Physiological Phenomena; D002543:Cerebral Hemorrhage / Q000134:cerebrospinal fluid / Q000503:physiopathology; D009638:Norepinephrine / Q000494:pharmacology*; D009994:Osmolar Concentration; D010841:Pia Mater / Q000098:blood supply*; D011453:Prostaglandins / Q000134:cerebrospinal fluid; D013552:Swine; D014661:Vasoconstriction
chemical_list: D011453:Prostaglandins; D000109:Acetylcholine; D009638:Norepinephrine