Central nervous system histamine regulates peripheral sympathetic activity.
Brain histamine (HA) was depleted in conscious Sprague-Dawley rats by central administration of alpha-fluoromethyl-histidine (alpha-FMH), an irreversible inhibitor of the HA synthesizing enzyme. Isotonic or hypertonic saline was infused intravenously at 10 microliters.100 g-1.min-1 for 30 min and mean arterial pressure (MAP) and heart rate (HR) were monitored. In addition, plasma vasopressin (AVP) and norepinephrine (NE) were measured pre- and postinfusion. Animals pretreated with alpha-FMH showed a delayed and attenuated pressor response and bradycardia during hypertonic saline (HTS) infusion and a significant reduction in plasma NE levels (-29 +/- 8% below control values). However, plasma concentrations of AVP were similar in both groups. Central pretreatment with the H1-antagonist pyrilamine (PYR) also delayed the onset and significantly attenuated the pressor response to HTS infusion, and caused dose-related decreases in plasma NE concentrations (-34 +/- 8, -47 +/- 5, and -52 +/- 7% after 60, 100, and 600 nmol PYR, respectively). These data indicate a role for central HA in peripheral sympathetic activation but not as a mediator of AVP release to a peripheral hyperosmotic stimulus.
Akins
V F
VF
Department of Physiology, University of Tennessee, Memphis 38163.
Bealer
S L
SL
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D002490:Central Nervous System / Q000378:metabolism*; D006632:Histamine / Q000378:metabolism / Q000502:physiology*; D006640:Histidine Decarboxylase / Q000037:antagonists & inhibitors; D008297:Male; D008762:Methylhistidines / Q000494:pharmacology; D009638:Norepinephrine / Q000097:blood; D010525:Peripheral Nerves / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D011738:Pyrilamine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011968:Receptors, Histamine / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure
D008762:Methylhistidines; D011968:Receptors, Histamine; D001127:Arginine Vasopressin; C028309:alpha-fluoromethylhistidine; D006632:Histamine; D006640:Histidine Decarboxylase; D011738:Pyrilamine; D009638:Norepinephrine