Linked Life Data

2719318

Source:http://linkedlifedata.com/resource/pubmed/id/2719318

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1989-6-12
pubmed:abstractText
The pulmonary artery responses in the isolated whole-blood perfused canine lung to ionized calcium ([Ca++]) were quantified over a range of hypercalcemia and hypocalcemia values ([Ca++] = 0.23-1.88 mM) under conditions of controlled pulmonary blood flow and constant mean aortic and left atrial pressures. Calcium chloride, administered as bolus doses in the clinical range (5-15 mg.kg-1) at initial normocalcemia and without interventions producing vasoconstriction did not influence mean pulmonary artery pressure at constant pulmonary blood flow. Stable hypercalcemia ([Ca++] = 1.88 +/- 0.05 mM) did not influence the slope of the pulmonary artery pressure-flow plot. Because normal pulmonary vasomotor tone is low and cannot readily be lowered further, the possible vasodilator action of hypocalcemia was assessed by its ability to decrease the slope of the mean pulmonary artery pressure-flow plot, which had been first increased by alveolar hypoxia (AHX) or infusion of the prostaglandin endoperoxide analog U46619 (PG). During AHX (n = 5), a graded reduction from normocalcemia ([Ca++] = 1.08 +/- 0.02 mM) to moderate hypocalcemia ([Ca++] = 0.8 and 0.5 mM) did not alter the pulmonary artery pressure-flow plot, but severe hypocalcemia ([Ca++] = 0.26 +/- 0.01 mM) decreased the slope by 13 +/- 0.9 mmHg.l-1.min-1. The comparison of severe hypocalcemia ([Ca++] = 0.23-0.27 mM) versus a high dose of nifedipine (bolus of 10 micrograms/kg followed by continuous infusion at 40 micrograms.kg-1.h-1) on pulmonary vascular tone increased by either AHX or PG infusion indicated that both hypocalcemia and nifedipine decreased the slope of the relationship between mean pulmonary artery pressure and flow (during AHX: -16.1 +/- 1.38 and -23.3 +/- 1.73 mmHg.l-1.min-1, both P = 0.0001 vs. AHX alone, and during PG: -17.05 +/- 1.95 and -8.4 +/- 1.78 mmHg.l-1.min-1, P = 0.0001 vs. PG alone). Two principal conclusions emerge. First, the pulmonary vessels are minimally sensitive to changes in ionized calcium throughout the clinical hypercalcemia and hypocalcemia ranges; extreme hypocalcemia is required to produce vasodilation, which was reversed with calcium infusion. Second, whereas the pulmonary vasodilator effects of extreme hypocalcemia were independent of the intervention inducing pulmonary vasoconstriction (AHX vs. PG), those of nifedipine were much more pronounced with AHX.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0003-3022
pubmed:author
pubmed:issnType
Print
pubmed:volume
70
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
825-36
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Pulmonary vascular responses to hypercalcemia and hypocalcemia in the dog.
pubmed:affiliation
Department of Anesthesia, Massachusetts General Hospital, Boston 02114.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't