President's message.
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Occupational Health Nursing↗
Biomedical subjects
J N Benoit
Publications and source records attributed to J N Benoit.
Increased hepatic oxygen consumption during alcohol withdrawal.
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Catecholamines↗
Effects of capacitative calcium entry on agonist-induced calcium transients in A7r5 vascular smooth muscle cells.
OBJECTIVE: The purpose of this study was to evaluate the contribution of capacitative calcium influx to intracellular calcium levels during agonist-induced stimulation of vascular smooth muscle cells. METHODS: Aortic vascular smooth muscle cells (A7r5) were loaded with Indo-1 and intracellular calcium transients were measured. Cells were challenged with either arginine vasopressin (0. 5 microM) or thapsigargin (1 microM). Lanthanum (1 mM) was used to block capacitative calcium influx through store-operated channels. Calcium traces were analyzed for basal, peak and plateau responses. Recordings were derivatized and integrated to gain additional information. Nonlinear regression provided a time constant that describes restoration of ionic equilibrium involving both sequestration and extrusion pathways. RESULTS: Stimulation of cells with thapsigargin produced a non-L-type calcium influx that was attenuated by lanthanum. Cells excited with vasopressin exhibited a rapid calcium increase followed by a gradual decrease to a plateau level. Lanthanum pretreatment prior to stimulation caused no significant change in baseline, peak or plateau calcium levels as compared to control. Lanthanum caused no significant change in maximal calcium release rate, calcium integrals or time constant as compared to control. CONCLUSIONS: Capacitative calcium entry can occur in vascular smooth muscle cells, but does not appear to contribute significantly to the vasopressin response.
Animals↗
Gene transfer to intact mesenteric arteries by electroporation.
The purpose of the present study was to develop a rapid, reproducible method of nonviral gene transfer to the intact vasculature. Male Sprague-Dawley rats were anesthetized, a midline abdominal incision was made and segmental branches of the superior mesenteric artery were dissected free of surrounding mesentery. A specially designed electroporation probe was placed around the neurovascular bundle and the electroporation chamber filled with a solution containing the firefly luciferase expressing plasmid (pCMV-Lux-DTS) or the green fluorescent protein expressing plasmid (pEGFP-N1). Vessels were electroporated with eight 10-ms pulses of 200 V/cm. Sixty seconds after electroporation, the DNA solution was removed, the intestine returned to the abdomen and the abdominal wall closed with suture and metal wound clips. Six hours to 5 days later, rats were sacrificed and electroporated vessels were recovered. Luciferase activity of the blood vessels was monitored. Gene expression was detected as early as 6 h postelectroporation, peaked at 1-3 days with levels up to 1 ng of reporter gene product per vessel segment and returned towards baseline by day 5. Histological analysis of blood vessel segments revealed green fluorescent protein-positive cells throughout the thickness of the vessel wall (endothelial cells to adventitia). Responses of electroporated vessels to vasoconstricting stimuli were indistinguishable from those of control vessels at either 2 or 40 days posttreatment. The results of this study provide evidence that electroporation is an effective means for introducing naked DNA into the blood vessel wall and form the basis for future studies on targeted gene therapy to the intact vasculature.
Animals↗