Autonomic Nervous System and Nitric Oxide Interactions

For lean healthy volunteers: * 20 subjects (10 males and 10 females) aged 18-60 yr. * All potential volunteers will have routine blood test to screen for hepatic, renal, and hematological abnormalities. * Body mass index \< 25Kg/m2 . * Female volunteers of childbearing potential will undergo HCG pregnancy test at screening and again on the study day. For Obese subjects with high blood pressure. * 20 subjects (10 males and 10 females) aged 18-60 yr. * All potential volunteers will have routine blood test to screen for hepatic, renal, and hematological abnormalities. * Body mass index \> 30 and less than 40 Kg/m2 \*High blood pressure (systolic=130 and diastolic = 85 mmHg) * Female volunteers of childbearing potential will undergo serum HCG pregnancy test at screening and urine HCG pregnancy test again on the study day. Exclusion criteria: * Pregnant females * Subjects unable to give voluntary informed consent * Subjects on anticoagulant drugs or anemic * Subjects with a recent medical illness * Subjects with a history of coronary heart disease * Subjects with known kidney or liver disease * Subjects with recent weight loss or consuming low carbohydrate diet