It has long been known that the adult circulation is controlled by interplay among neural and local tissue mechanisms. But a largely unsolved question is when during postnatal development does each mechanism before effective. Differences in the time-course of postnatal development of the peripheral neural vasoconstrictor and local vasodilator systems in the regulation of blood flow are being investigated in anesthetized swine of various ages. Both physiologic and pharmacologic approaches are used. Arterial pressure is registered by strain gauge transducer, and flow by non-cannulating electromagnetic transducer. Three vascular beds have been selected for study. The role of neural activity is assessed in experiments involving denervation and stimulation of sympathetic efferent fibers. Autoregulatory control is assessed by step-changes in perfusion pressure via compression of the aorta below the diaphragm to provide immediate and delayed changes in vascular resistance as evidence for the presence and range of blood flow autoregulation. Experiments on the renal and femoral circulations have been completed. Ongoing research on the intestinal circulation has progressed to include experiments comparing the ileal and jejunal vascular beds, which provide blood to intestinal segments having somewhat different transport functions. In the proposed continuation of this investigation, controlled-pressure protocols will be carried out, responses to postganglionic sympathetic denervation and nerve stimulation will be determined, and responses to single injections and continuous infusion i.a. of vasoactive compounds will be evaluated. The effects of the latter will be assessed in terms of alterations in perfusion pressure during controlled-flow perfusion of ileal and jejunal segments, and of """"""""autoregulatory escape."""""""" In both the ongoing and new experiments, differences between neurally and locally mediated responses will be examined at each age by statistical analysis of the incidence and magnitude of effects, and differences between age groups will be sought. The long-term goal to examine regional circulatory responses during physiologic stress will then be regional blood flow distribution (among kidney, hindlimb, and ileum or jejunum) and blood flow autoregulation during experimentally induced in creases in the local demand for blood flow, by increasing skeletal muscle work or intestinal activity.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL021865-08
Application #
3336646
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1978-12-01
Project End
1989-03-29
Budget Start
1987-09-30
Budget End
1989-03-29
Support Year
8
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
Buckley, N M; Frasier, I D (1990) Regional circulatory responses to intestinal work in developing swine. Am J Physiol 258:H1119-25
Buckley, N M; Frasier, I D (1990) Regional circulatory responses to hindlimb work in developing swine. Biol Neonate 58:208-19
Buckley, N M; Diamant, S; Frasier, I D et al. (1988) Histamine or adenosine blockade alters intestinal blood flow autoregulation in swine. Am J Physiol 254:G156-61
Buckley, N M; Diamant, S; Frasier, I D et al. (1988) Vasoactive compound effects on autoregulating versus nonautoregulating intestinal and renal circulations in young swine. Biol Neonate 54:49-59
Buckley, N M; Jarenwattananon, M; Gootman, P M et al. (1987) Autoregulatory escape from vasoconstriction of intestinal circulation in developing swine. Am J Physiol 252:H118-24
Buckley, N M; Brazeau, P; Frasier, I D (1986) Intestinal and femoral blood flow autoregulation in developing swine. Biol Neonate 49:229-40
Buckley, N M; Brazeau, P; Frasier, I D et al. (1985) Circulatory effects of splanchnic nerve stimulation in developing swine. Am J Physiol 248:H69-74