Vascular Studies
After 4 weeks of feeding, rats were sacrificed by cervical dislocation. The section of the aorta from between the aortic arch and the diaphragm was removed from the euthanized rats and placed in oxygenated, modified Krebs-Henseleit solution (KHS; in mM: 118 NaCl, 4.7 KCl, 25 NaHCO3, 2.6 CaCl2 2H2O 1.2 NaH2PO4, 1.2 MgCl2 6H2O, 5.5 glucose). With the help of a steel rod, aortic endothelium was deliberately denuded. The aorta was cut into helical strips 3 mm wide, 20 mm long and then placed in a well-oxygenated (95% O2-5% CO2) bath of 10-ml KHS with one end connected to a tissue holder and the other to an isotonic transducer (Bio Devices, Ambala, India). The tissue was equilibrated for 60 min under a resting tension of 1.0 g. At the beginning of each experiment, aortic strips were primed with depolarizing concentration (90 mM) potassium chloride (KCl). After the equilibration period, contractile responses to various concentrations of 5-HT (10 nM-30 μM) and Ang II (1 nM-300 nM) were recorded.