TY - JOUR
T1 - The effect of sarcoplasmic reticulum blockade on the force/frequency relationship and systolic contraction patterns in the newborn pig heart
AU - Klautz, Robert J. M.
AU - Baan, Jan
AU - Teitel, David F.
PY - 1997
Y1 - 1997
N2 - We investigated the relationship between heart rate and contractility in seven anaesthetized young piglets by measuring contractility at different atrial pacing rates. To study the origin of this relationship we repeated the measurements after blocking the sarcoplasmic reticulum calcium release channel with ryanodine. We assessed contractility using indices derived from instantaneous left ventricular pressure and volume measured by micromanometric and conductance catheters during rapid inferior vena cava occlusion, thus generating the end-systolic pressure-volume relationship, which was characterized by its slope E(es), and the maximum rate of change of ventricular pressure (dP/dt(max))/end-diastolic volume relationship, also characterized by its slope. All animals showed an increase in contractility with increasing heart rate (intact force/frequency relationship) which was abolished after ryanodine. The most striking effect of ryanodine on baseline haemodynamics was the dramatic decrease of dP/dt(max) to about 50% of its original value, while peak developed pressure and E(es) did not change. We conclude that the young piglet, despite its immaturity, has a functional sarcoplasmic reticulum, illustrated by an intact force/frequency relationship. In addition, blockade of the sarcoplasmic reticulum in vivo has profoundly different effects during early and late systole, indicating that indices of contractility derived during different parts of the cardiac cycle represent different aspects of systole.
AB - We investigated the relationship between heart rate and contractility in seven anaesthetized young piglets by measuring contractility at different atrial pacing rates. To study the origin of this relationship we repeated the measurements after blocking the sarcoplasmic reticulum calcium release channel with ryanodine. We assessed contractility using indices derived from instantaneous left ventricular pressure and volume measured by micromanometric and conductance catheters during rapid inferior vena cava occlusion, thus generating the end-systolic pressure-volume relationship, which was characterized by its slope E(es), and the maximum rate of change of ventricular pressure (dP/dt(max))/end-diastolic volume relationship, also characterized by its slope. All animals showed an increase in contractility with increasing heart rate (intact force/frequency relationship) which was abolished after ryanodine. The most striking effect of ryanodine on baseline haemodynamics was the dramatic decrease of dP/dt(max) to about 50% of its original value, while peak developed pressure and E(es) did not change. We conclude that the young piglet, despite its immaturity, has a functional sarcoplasmic reticulum, illustrated by an intact force/frequency relationship. In addition, blockade of the sarcoplasmic reticulum in vivo has profoundly different effects during early and late systole, indicating that indices of contractility derived during different parts of the cardiac cycle represent different aspects of systole.
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0031418154&origin=inward
UR - https://www.ncbi.nlm.nih.gov/pubmed/9359912
U2 - https://doi.org/10.1007/s004240050492
DO - https://doi.org/10.1007/s004240050492
M3 - Article
C2 - 9359912
SN - 0031-6768
VL - 435
SP - 130
EP - 136
JO - Pflugers Archiv
JF - Pflugers Archiv
IS - 1
ER -