Effect of vitamin A deficiency on cardiovascular function in the rat.
Selected parameters of cardiovascular function were evaluated in vitamin A-deficient rats at 70 days of age. Resting heart rate was increased by an average of 100 bpm (21.4+/-2.7%), whereas resting systolic blood pressure was normal in vitamin A-deficient animals. The maximal contractile force developed per milligram weight of tissue by aortic rings excised from vitamin A-deficient animals was reduced in response to high potassium (-25.0+/-8.7%) and phorbol 12,13-dibutyrate (-36.8+/-8.4%) but was only slightly reduced in response to norepinephrine (-17.8+/-11.1%). Intimal rubbing to remove the endothelium had no effect on the loss in contractile responsiveness, and the relaxant response to acetylcholine was similar between control and vitamin A-deficient tissue groups. This suggests that the decrease in contractility of vascular smooth muscle from the vitamin A-deficient rats did not involve altered release of endothelium-derived vasoactive factors. Western blot analysis suggested a reduction in the protein levels of several differentiation markers including alpha-actin (-22%), calponin (-37%), desmin (-37%), and vinculin (-40%), whereas the level of PKCalpha was unchanged from control values. Our findings indicate a significant decrease in contractile responsiveness of aortic smooth muscle of the vitamin A-deficient rat that may be associated with a down regulation in the expression of contractile-related proteins.
Wright
G L
GL
Department of Physiology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25704, USA. wrightg@marshall.edu
Wang
S
S
Fultz
M E
ME
Arif
I
I
Matthews
K
K
Chertow
B S
BS
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001794:Blood Pressure / Q000502:physiology; D015153:Blotting, Western; D001835:Body Weight / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009929:Organ Size / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014802:Vitamin A Deficiency / Q000503:physiopathology*
D011506:Proteins