July 1, 1995Endocrinology
The hemodynamic basis for the cardiac effects of parathyroid hormone (PTH) and PTH-related protein.
Key result
PTH and PTHrP act as inotropic agents by influencing coronary flow and heart rate, but have no direct effect on contractile elements in the heart.
Why the study?
Do PTH and PTHrP have direct inotropic effects on isolated perfused rat hearts independent of chronotropic and coronary flow changes?
Population
Isolated perfused rat hearts
Comparison
Parathyroid hormone and PTH-related protein vs Different experimental conditions
Design
Preclinical
Authors
Discussion
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Implication
Indirect PTH cardiac effects merit monitoring in endocrine patients; leaves open direct inotropic roles for prospective validation.
Structured PICO
Do PTH and PTHrP have direct inotropic effects on isolated perfused rat hearts independent of chronotropic and coronary flow changes?
P
Population
Isolated perfused rat hearts divided into three experimental groups to assess the direct inotropic effects of PTH and PTHrP.
I
Intervention
Parathyroid hormone (PTH) and PTH-related protein (PTHrP)
C
Comparator
Different experimental conditions (control group with variable heart rate and coronary flow; second group with fixed heart rate; third group with fixed heart rate and constant coronary flow via maximal prevasodilation with nitroprusside)
O
Outcome
Direct inotropic effects (measured by peak pressure [LVPmax], peak rate of rise of LV pressure [dP/dtmax], and peak intracellular calcium)surrogate
PTH and PTHrP exert inotropic effects indirectly through changes in coronary flow and heart rate, rather than via direct action on myocardial contractile elements.
Cite This Study
Ogino et al. (1995) studied this question. Parathyroid hormone (PTH) and PTH-related protein (PTHrP) vs. Different experimental conditions (fixed heart rate, fixed coronary flow) was evaluated on Peak pressure (LVPmax), peak rate of rise of LV pressure (dP/dtmax), and peak intracellular calcium. PTH and PTHrP act as inotropic agents by influencing coronary flow and heart rate, but have no direct effect on contractile elements in the heart.