Effects of adrenergic and cholinergic drugs on splenic arteries and veins from hooded seals (Cystophora cristata).
Isolated ring preparations of arteries and veins from hooded seal spleens were subjected in vitro to adrenaline (A), noradrenaline (NA), isoprenaline (Iso), and acetylcholine (ACh), alone or in combination with the blockers phentolamine (Phe), propranolol (Pro), and atropine (Atr). Both arteries and veins constricted in response to A (the estimated effective dose required for half-maximal response (ED50) was 3.3 and 0.2 microM, for arteries and veins, respectively) and NA (estimated ED50 was 1.5 and 0.6 microM, for arteries and veins, respectively), but these effects were abolished when the drugs were given in combination with the alpha-adrenoceptor blocker Phe. The responses of arteries and veins to ACh and the beta-adrenoceptor agonist Iso were minor and inconsistent, and were completely abolished when combined with their respective blockers (Atr and Pro, respectively). The ED50 for both A and NA are quite high in relation to normal plasma levels of A and NA in seals. This implies that these vessels (and, hence, the supply of blood to the spleen) primarily are subjected to neurogenic, rather than humoral physiological control.
Department of Arctic Biology, University of Tromsø, Norway.
A
A
Cabanac
L P
LP
Folkow
A S
AS
Blix
D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D018678:Cholinergic Agents / Q000494:pharmacology*; D005260:Female; D008297:Male; D046048:Seals, Earless / Q000502:physiology*; D013157:Splenic Artery / Q000187:drug effects*; D013162:Splenic Vein / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects
D018663:Adrenergic Agents; D018678:Cholinergic Agents