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Articles by Bridget Mahon Seitz
Total Records ( 1 ) for Bridget Mahon Seitz
  Bridget Mahon Seitz and Stephanie W. Watts
  Background: Long-term serotonin (5-hydroxytryptamine, 5-HT) infusion produces a sustained reduction in mean arterial pressure (MAP) and a decrease in total peripheral resistance (TPR) through a mechanism dependent on Nitric Oxide Synthase (NOS) in rats. This study sought to determine if the reduction in resistance induced by 5-HT is caused by NOS-dependent relaxation of vessels to all major organs of the body or in a specific vascular bed. Materials and Methods: Alzet mini-pumps containing vehicle (saline) or 5-HT (25 μg kg-1 min-1) were implanted in male Sprague Dawley rats. A separate group of rats was treated with the NOS inhibitor Nω-nitro-L-arginine (LNNA; 0.5 g L-1) prior to 5-HT administration. Results: 5-HT reduced MAP after 24 h (veh = 87±3, 5-HT = 75±2 mm Hg; p<0.05), a fall prevented by LNNA (LNNA/5-HT= 115±10 mm Hg). Yellow-green fluorescent microspheres, used to measure blood flow (300, 000 spheres; size 15 μm), were introduced into the left ventricle of the heart. Microspheres were recovered in arterial reference blood sample and organs using sedimentation through centrifugation. The intensity of dye extracted from the microspheres was measured spectrophotometrically. The 5-HT significantly decreased resistance to the spleen (48%) and small intestine (35%) compared to vehicle-treated animals; this decrease was abolished by LNNA. By contrast, resistance to the ear (175%) was increased by 5-HT. Resistance in brain, liver, lungs, kidneys and muscle did not show a statistically significant reduction by 5-HT. Conclusion: These findings underscore the importance of the splanchnic (particularly intestinal) circulation and NOS in 5-HT-induced reduction in blood pressure.
 
 
 
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