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Role of epinephrine in 5HT 1A receptor agonist‐mediated increase in venous tone during hypovolemic shock
Author(s) -
Tiniakov Ruslan L,
Scrogin Karie E
Publication year - 2010
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.24.1_supplement.625.15
Subject(s) - medicine , mean circulatory filling pressure , anesthesia , hemodynamics , shock (circulatory) , splanchnic , epinephrine , blood pressure , saline , mean arterial pressure , central venous pressure , blood volume , endocrinology , heart rate
The 5‐HT 1A receptor agonist, 8‐OH‐DPAT, improves hemodynamic parameters and tissue oxygenation during hypovolemic shock via splanchnic sympathetic nerve‐dependent increases in venous tone. To determine if endogenous epinephrine contributes to this response, effects of 8‐OH‐DPAT (30 nmol/kg, iv) and saline on arterial pressure (AP) and mean circulatory filling pressure (MCFP, an index of venous tone) were measured in adrenal‐demedullated (ADMX) and sham‐operated rats during fixed‐pressure (FPH) and fixed‐volume (FVH) hemorrhagic shock. ADMX rats had lower baseline MCFP (5.4 ± 0.1 vs. 7.5 ±0.2 mmHg; P < 0.01) and reached an AP of 50 mmHg with less blood loss (31.3 ± 0.9 vs. 35.0 ± 0.4 ml/kg; P <0.01) than sham‐operated rats. In both hemorrhage models, 8‐OH‐DPAT produced a rapid and persistent pressor effect in sham‐ and ADMX rats (FPH: +29 ± 5 and +28 ± 3 mmHg, P <0.01; FVH: +34 ± 4 mmHg and +36 ± 4 mmHg, P <0.01). This was paralleled by a persistent increase in MCFP in sham‐operated rats (+1.6 ± 0.4 and +1.9 ± 0.4 mmHg, 5 and 35 min after injection, FVH; P <0.01), but only a transient increase in ADMX rats (+1.1 ± 0.4 mmHg, P <0.05, and +0.4 ± 0.4 mmHg, 5 and 35 min post injection, FVH). Saline had no effect on AP or MCFP in either hemorrhage model. Blood volume before FVH (50 ± 1 vs. 53 ± 2 ml/kg) and after treatment with 8‐OH‐DPAT (31 ± 2 vs. 31 ± 5 ml/kg) did not differ between sham‐ and ADMX rats. The data indicate that persistent elevation of MCFP induced by 8‐OH‐DPAT in hypovolemic rats, but not the rise in AP, is mediated, in part, by endogenous epinephrine. Supported by HL 076162.