Abstract
Objective. To clarify the controversial issue of whether autonomic influences modulate vascular nitric oxide-mediated vasodilatation or even directly contribute to production of nitric oxide (NO) via nitroxidergic fibers. Methods. Chronic venous and arterial catheters were implanted in Wistar-Kyoto rats (n = 65) for continuous blood pressure measurement, drug administration and blood sampling. Tonic NO-dependent vasodilatation in the conscious free-moving animal was evaluated as the pressor response to inhibition of NO synthesis by intravenous L-monomethylarginine (a 100 mg/kg intravenous bolus plus 0.5 mg/kg per min infusion for 30 min). Experiments were performed under control conditions, chemical sympathectomy by 6-hydroxy-dopamine, ganglionic blockade by hexamethonium, and surgical denervation of sino-aortic baroreceptors. Results. Baseline mean arterial pressure was 100 ± 4 mmHg (mean ± SEM) in control rats and 73 ± 3, 62 ± 5, and 105 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. The peak increase in mean arterial pressure after administration of L-monomethylarginine was 38 ± 3 mmHg in control rats and 51 ± 3, 50 ± 6, and 63 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. Epinephrine and norepinephrine levels in rats of separate groups of unanesthetized control, sympathectomized and ganglion-blocked animals were measured by high-performance liquid chromatography from an arterial blood sample, the results indicating drastic reductions in levels of both catecholamines in the ganglion-blocked (but not in the sympathectomized) rats compared with those in the control rats. Conclusions. Tonic NO-dependent vasodilatation can normally be maintained in the unanesthetized unrestrained rat irrespective of autonomic or humoral adrenergic influences.
| Original language | English |
|---|---|
| Pages (from-to) | 55-61 |
| Number of pages | 7 |
| Journal | Journal of Hypertension |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1998 |
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Keywords
- Blood pressure
- Ganglionic blockade
- L-nitromonomethyl-L-arginine
- Nitric oxide
- Sino-aortic denervation
- Sympathectomy
- Unanesthetized rat
ASJC Scopus subject areas
- Endocrinology
- Internal Medicine
Cite this
Lack of autonomic contributions to tonic nitric oxide-mediated vasodilatation in unanesthetized free-moving rats. / Radaelli, Alberto; Mircoli, Luca; Perlini, Stefano; Bolla, Gianni; Mori, Ileana; Mancia, Giuseppe; Ferrari, Alberto U.
In: Journal of Hypertension, Vol. 16, No. 1, 1998, p. 55-61.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Lack of autonomic contributions to tonic nitric oxide-mediated vasodilatation in unanesthetized free-moving rats
AU - Radaelli, Alberto
AU - Mircoli, Luca
AU - Perlini, Stefano
AU - Bolla, Gianni
AU - Mori, Ileana
AU - Mancia, Giuseppe
AU - Ferrari, Alberto U.
PY - 1998
Y1 - 1998
N2 - Objective. To clarify the controversial issue of whether autonomic influences modulate vascular nitric oxide-mediated vasodilatation or even directly contribute to production of nitric oxide (NO) via nitroxidergic fibers. Methods. Chronic venous and arterial catheters were implanted in Wistar-Kyoto rats (n = 65) for continuous blood pressure measurement, drug administration and blood sampling. Tonic NO-dependent vasodilatation in the conscious free-moving animal was evaluated as the pressor response to inhibition of NO synthesis by intravenous L-monomethylarginine (a 100 mg/kg intravenous bolus plus 0.5 mg/kg per min infusion for 30 min). Experiments were performed under control conditions, chemical sympathectomy by 6-hydroxy-dopamine, ganglionic blockade by hexamethonium, and surgical denervation of sino-aortic baroreceptors. Results. Baseline mean arterial pressure was 100 ± 4 mmHg (mean ± SEM) in control rats and 73 ± 3, 62 ± 5, and 105 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. The peak increase in mean arterial pressure after administration of L-monomethylarginine was 38 ± 3 mmHg in control rats and 51 ± 3, 50 ± 6, and 63 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. Epinephrine and norepinephrine levels in rats of separate groups of unanesthetized control, sympathectomized and ganglion-blocked animals were measured by high-performance liquid chromatography from an arterial blood sample, the results indicating drastic reductions in levels of both catecholamines in the ganglion-blocked (but not in the sympathectomized) rats compared with those in the control rats. Conclusions. Tonic NO-dependent vasodilatation can normally be maintained in the unanesthetized unrestrained rat irrespective of autonomic or humoral adrenergic influences.
AB - Objective. To clarify the controversial issue of whether autonomic influences modulate vascular nitric oxide-mediated vasodilatation or even directly contribute to production of nitric oxide (NO) via nitroxidergic fibers. Methods. Chronic venous and arterial catheters were implanted in Wistar-Kyoto rats (n = 65) for continuous blood pressure measurement, drug administration and blood sampling. Tonic NO-dependent vasodilatation in the conscious free-moving animal was evaluated as the pressor response to inhibition of NO synthesis by intravenous L-monomethylarginine (a 100 mg/kg intravenous bolus plus 0.5 mg/kg per min infusion for 30 min). Experiments were performed under control conditions, chemical sympathectomy by 6-hydroxy-dopamine, ganglionic blockade by hexamethonium, and surgical denervation of sino-aortic baroreceptors. Results. Baseline mean arterial pressure was 100 ± 4 mmHg (mean ± SEM) in control rats and 73 ± 3, 62 ± 5, and 105 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. The peak increase in mean arterial pressure after administration of L-monomethylarginine was 38 ± 3 mmHg in control rats and 51 ± 3, 50 ± 6, and 63 ± 10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. Epinephrine and norepinephrine levels in rats of separate groups of unanesthetized control, sympathectomized and ganglion-blocked animals were measured by high-performance liquid chromatography from an arterial blood sample, the results indicating drastic reductions in levels of both catecholamines in the ganglion-blocked (but not in the sympathectomized) rats compared with those in the control rats. Conclusions. Tonic NO-dependent vasodilatation can normally be maintained in the unanesthetized unrestrained rat irrespective of autonomic or humoral adrenergic influences.
KW - Blood pressure
KW - Ganglionic blockade
KW - L-nitromonomethyl-L-arginine
KW - Nitric oxide
KW - Sino-aortic denervation
KW - Sympathectomy
KW - Unanesthetized rat
UR - http://www.scopus.com/inward/record.url?scp=0031942682&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031942682&partnerID=8YFLogxK
U2 - 10.1097/00004872-199816010-00010
DO - 10.1097/00004872-199816010-00010
M3 - Article
C2 - 9533418
AN - SCOPUS:0031942682
VL - 16
SP - 55
EP - 61
JO - Journal of Hypertension
JF - Journal of Hypertension
SN - 0263-6352
IS - 1
ER -