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Adenosine A 2a receptors in the nucleus of the solitary tract (NTS) do not reset baroreflex functions for renal (RSNA) and adrenal (ASNA) sympathetic nerve activity
Author(s) -
Ichinose Tomoko K,
O'Leary Donal S,
Scislo Tadeusz J
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1171.11
Subject(s) - chemistry , baroreflex , medicine , endocrinology , phenylephrine , agonist , antagonist , stimulation , receptor , blood pressure , heart rate , biochemistry
Stimulation of NTS A 2a adenosine receptors elicits ‘baroreflex‐like’ decreases in mean arterial pressure (MAP), heart rate and RSNA. In contrast, increases in ASNA occur (AJP 275: H2130‐2139, 1998; AJP 278: H2057‐2068, 2000). Therefore we investigated if NTS A 2a receptors affect baroreflex control of RSNA and ASNA. We compared full baroreflex‐response curves (i.v. nitroprusside/phenylephrine) evoked before and after bilateral microinjections into the NTS of selective adenosine A 2a receptor agonist (CGS‐21680, 20 pmol/50nL, n=6) or antagonist (ZM‐241385, 40pmol/100nL, n=7) in urethane/α‐chloralose anesthetized male Sprague Dawley rats. CGS‐21680 evoked typical depressor (−23.8 ± 6.2 mmHg) and differential nerve responses (RSNA; −64.7 ± 4.4 Δ%, ASNA; +98.2 ± 11.5 Δ%). In contrast, ZM‐241385 increased RSNA (+10.5 ± 2.8 Δ%) and decreased ASNA (−2.2 ± 0.7 Δ%) without altering MAP. Both the agonist and antagonist did not reset RSNA and ASNA baroreflex curves along the MAP axis. The A 2a agonist decreased the range, upper plateau and maximal gain (G max ) of baroreflex curve for RSNA and increased G max and upper plateau for ASNA, the changes consistent with the direct action of the agonist. The A 2a antagonist increased the range and upper plateau for RSNA only. We conclude that activation of NTS A 2a receptors decreases RSNA and increases ASNA mostly via some non‐baroreflex mechanism(s). NIH HL‐67814