title: Effect of fasting on vascular contractility in lean and obese Zucker rats.
abstract: We compared the effects of fasting (36 h) on blood pressure and aortic contractile responsiveness in lean and obese Zucker rats. Fasting of lean animals resulted in a significant loss in body weight (-9.1 +/- 0.1%) and reduction in systolic blood pressure (-11.4 +/- 1.9 mmHg). Fasting plasma triacylglycerols (-76%) and beta-hydroxybutryic acid (beta-HBA) (+ 218%) were significantly decreased and increased, respectively. The fasting plasma concentrations of insulin (-72%) were significantly decreased, whereas glucose and epinephrine (Epi) were not changed in lean rats. The fasting of obese rats also resulted in weight loss (-5.6 +/- 1.3%) but did not cause a significant reduction of blood pressure. The plasma total cholesterol (+18%) was increased, triacylglycerols (-42%) were decreased and beta-HBA levels were unchanged in fasted obese rats. Similar to lean animals, the insulin levels of fasted obese rats were significantly decreased (-85%), whereas glucose and Epi concentrations were not significantly changed. Fasting of lean animals had no effect on the maximal contractile response of aortae to high K(+) and phorbol 12, 13 dibutyrate (PDBu) but significantly reduced the response to norepinephrine (NE) (% reference: fed, 61.1 +/- 11.0; fasted, 45.6 +/- 4.5). In addition, the concentration for half-maximal response (ED(50)) to NE was increased in fasted lean rats (fed, 1.8+/-0.2 x 10(-8)M; fasted, 3.0+/-0.3 x 10(-8)M). By comparison, fasting of obese rats had no significant effect on the contractile response to K(+), NE, or PDBu. The results show that short-term food withdrawal induces significant changes in vascular contractile properties of lean but not obese rats. Because fasting-induced changes were variable depending on the agonist, the results further suggest that the mechanism did not involve a general loss or enhancement in functional status.
authors.affiliation: Departments of Physiology, The Joan Edwards School of Medicine, Marshall University, Huntington, WV 25704, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Wright
authors.forename: R
authors.initials: R
authors.lastname: Morrison
authors.forename: M E
authors.initials: ME
authors.lastname: Fultz
authors.forename: G
authors.initials: G
authors.lastname: Wright
authors.forename: W
authors.initials: W
authors.lastname: Mccumbee
authors.forename: P
authors.initials: P
authors.lastname: Wehner
authors.forename: M
authors.initials: M
authors.lastname: Studeny
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D004195:Disease Models, Animal; D004837:Epinephrine / Q000097:blood; D005215:Fasting / Q000502:physiology*; D005260:Female; D007328:Insulin / Q000097:blood; D009119:Muscle Contraction / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000097:blood; D009765:Obesity / Q000097:blood / Q000235:genetics / Q000503:physiopathology*; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness / Q000097:blood / Q000503:physiopathology*; D014280:Triglycerides / Q000097:blood; D015431:Weight Loss / Q000502:physiology
chemical_list: D007328:Insulin; D014280:Triglycerides; D020155:3-Hydroxybutyric Acid; D009638:Norepinephrine; D004837:Epinephrine