[Adenosine facilitates carotid baroreflex in rats].
The effects of adenosine (Ado) on the carotid baroreflex were studied in 27 anesthetized rats with isolated carotid sinus perfusion. The results obtained were as follows: (1) By perfusing the isolated carotid sinus with adenosine (125 mumol/L), the functional curve of baroreflex was shifted to the left and downward, with the peak slope (PS) increased from 0.37 +/- 0.02 to 0.55 +/- 0.02 kPa/kPa (P < 0.001) and the reflex decrease in mean arterial pressure (RD) enhanced from 5.53 +/- 0.12 to 7.76 +/- 0.36 kPa (P < 0.001). Meanwhile, the threshold pressure (TP), equilibrium pressure (EP) and saturation pressure (SP) were significantly decreased from 8.60 +/- 0.27 to 5.63 +/- 0.11 kPa (P < 0.001), 12.53 +/- 0.30 to 10.89 +/- 0.29 kPa (P < 0.01) and 23.69 +/- 0.15 to 20.18 +/- 0.55 kPa (P < 0.001), respectively. Among the functional parameters of carotid baroreflex, the changes of RD, PS and TP induced by Ado were dose-dependent. (2) By pretreatment with (8-cyclopentyl-1, 3-dipropylxanthine, 0.134 mmol/L), a selective adenosine A1-receptor antagonist, the above effects of Ado on carotid baroreflex were abolished. (3) The Ado-induced changes of baroreflex were also eliminated as the carotid sinus was pretreated with KATP channel blocker glibenclamide (10 mumol/L). The results strongly suggest that the carotid baroreflex could be facilitated by Ado. It is proposed that the facilitatory action of Ado on carotid baroreflex may be resulted from the opening of KATP channels mediated by Ado A1-receptors.
Chen
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Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017.
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D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects*; D002346:Carotid Sinus / Q000502:physiology*; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000187:drug effects*; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D014970:Xanthines / Q000494:pharmacology
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D058915:Purinergic P1 Receptor Antagonists; D014970:Xanthines; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine; D011188:Potassium; D005905:Glyburide