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Noxious visceral stimulation and the response to blood loss in conscious rabbits
Author(s) -
Shafford Heidi L,
Ivey Jan R,
McKown Michael D,
Scherff Eric J,
Schadt James C
Publication year - 2006
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.20.5.a1383-d
Subject(s) - medicine , anesthesia , blood pressure , heart rate , mean arterial pressure , respiratory rate , visceral pain , arterial blood , distension , hemodynamics , diaphragmatic breathing , nociception , receptor , alternative medicine , pathology
Pain is a component of traumatic blood loss, yet few studies have evaluated the effect of pain on the response to blood loss in conscious animals. We evaluated the cardiovascular and respiratory effects of colorectal distension (CRD) as a model of visceral pain first in anesthetized and then in conscious New Zealand white rabbits. All rabbits were chronically instrumented with arterial and venous catheters and diaphragmatic EMG leads. CRD (n = 5) resulted in reproducible and reversible changes in mean arterial pressure [ΔMAP; 12 ± 1 mmHg (mean ± SE)], heart rate (ΔHR; 14 ± 5 bpm) and respiratory rate (ΔRR; −60 ± 18 bpm) from control values of 73 ± 2 mmHg, 150 ± 4 bpm and 188 ± 27 bpm, respectively. Pretreatment with buprenorphine, an opioid analgesic, blunted these cardiovascular and respiratory changes (ΔMAP = 4 ± 2 mmHg; ΔHR = 5 ± 5 bpm; ΔRR = −27 ± 16 bpm). We hypothesized that CRD would enhance arterial blood pressure maintenance during blood loss. Venous blood was withdrawn until MAP decreased to ≤ 40 mmHg. The experiment was repeated with and without (Control) CRD initiated prior to and sustained throughout the blood loss. CRD (n = 4) increased MAP (17 ± 5 mmHg) and HR (19 ± 5 bpm), and decreased RR (58 ± 26 bpm). Blood loss required to produce hypotension was 22.4 ± 0.8 ml/kg during CRD and 21.7 ± 0.8 ml/kg during Control. Thus, in conscious rabbits, CRD alters cardiovascular and respiratory control, and may influence the response to blood loss. CRD in conscious rabbits appears to be a useful model for evaluating the interaction between pain and cardiovascular control. Supported by NIH and ONR.