Abstract
Studies were performed to determine the effect of nitrates (pentrinitrol and nitroglycerin) and a beta adrenergic blocking agent (propranolol) on the distribution of blood within various chambers and regions of the heart. Asphyxia was studied to determine if myocardial small vessel blood content was maximal under basal conditions. Small vessel blood content was measured with 59FeCl3 which labels the plasma siderophilin. Under basal conditions, blood content of the left ventricular free wall > septum > right ventricular free wall. Gradients of blood content were present with the deep regions containing more blood than the superficial and the apex more than the base. Pentrinitrol, 80 µg/kg i.v., and nitroglycerin, 20 µg/kg i.v., had no significant effect on absolute blood content nor were the gradients altered. Propranolol, 1.0 mg/kg i.v., decreased myocardial blood content. Transmural gradients were not altered but gradients from base to apex were reduced. Asphyxia significantly increased small vessel blood content and abolished or reduced the gradients within the free ventricular walls. The increase in blood content produced by asphyxia demonstrates that blood content is not maximal under basal anesthetized conditions. The greater uniformity of small vessel blood content within the free ventricular walls after asphyxia suggests that the gradients reflect functional rather than anatomical adaptations of vascular density.
Footnotes
- Received May 17, 1973.
- Accepted August 2, 1973.
- © 1973 by The Williams & Wilkins Co.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|