CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 1, January/February 2013
AFRICA
283
Dialysed plasma from mature rabbits undergoing rIPC protects
isolated mature rabbit hearts in a Langendorff model, but the effect
on the neonatal heart is unknown. The neonatal heart relies almost
solely on carbohydrate metabolism, known to be modified by rIPC
in the mature heart. We used microdialysis combined with targeted
metabolomics to profile metabolism in the immature rabbit heart.
Hypothesis:
Treatment of neonatal rabbit hearts prior to ischae-
mia–reperfusion injury with either
in vivo
rIPC or perfusion with
dialysate from adult rIPC-treated rabbits alters myocardial function
and metabolism and may be detrimental.
Methods:
Fifteen newborn (1–4 days old, 49–72 g) rabbits were
randomised into three groups (
n
=
5 in each group): control,
in vivo
rIPC and adult rIPC dialysate group. Plasma from the rIPC-treated
adult rabbits was dialysed, added to the buffer and administered to
the dialysate group. Hearts were mounted in a Langendorff model
and perfused for 55 min stabilisation, 40 min global ischaemia and
120 min reperfusion. A microdialysis probe was inserted intramurally
in the LV and samples (10
μ
l) were analysed using UPLC-MS/MS,
targeting lactate and purine metabolites.
Results:
During the final 10 min of ischaemia, interstitial lactate
concentration almost doubled in the rIPC (7.8
±
1.0 mM/l) and
dialysate group (9.3
±
0.6 mM/l) compared with the controls (4.6
±
0.1 mM/l) (
p
<
0.05). Simultaneously, a marked increase in inosine
concentrations was measured for the intervention group: rIPC (49.2
±
4.0
μ
M/l) and dialysate group (52.5
±
9.6
μ
M/l) compared to the
controls (17.2
±
6.0
μ
M/l) (
p
<
0.05). Functional recovery (dP/dt
min) during 30 min reperfusion was impaired in the rIPC (–329.4
±
34 mmHg) and the rIPC dialysate (–270.3
±
65 mmHg) groups
compared to the controls (–683.8
±
56 mmHg) (
p
<
0.05).
Conclusions:
In vivo
rIPC and rIPC dialysate increased cyto-
solic energy expenditure during ischaemia and attenuated functional
recovery in the neonatal isolated rabbit heart.
731: PLATELET FUNCTION AND MORPHOLOGY IN IDIO-
PATHIC PULMONARY HYPERTENSION
Ramakrishnan Sivasubramanian, NB Senguttuvan, R Lakshmy, Renu
Saxena, S Wadhwa, JM Khunger, B Bhargava, SS Kothari, A Saxena,
VK Bahl
All India Institute of Medical Sciences, New Delhi, India
Background:
Thrombosis and proliferation are two important
pathological features of idiopathic pulmonary hypertension (IPAH).
Theoretically, both these processes may be initiated by platelets. A
barrage of activated platelets in the pulmonary circulation, similar to
what happens in the nail bed to cause clubbing, may lead to all the
known pathological changes seen in iPAH.
Methods:
Nine consecutive patients of iPAH [median age 24 years
(14–47 years)] were included in the study. Nine patients with rheu-
matic heart disease with pulmonary hypertension [median age 42
years (22–66 years)] were recruited as controls. Blood samples were
taken from the superior vena cava, pulmonary artery, left ventricle
and femoral artery. Collagen and adenosine-di-phosphate were
utilised for the assessment of platelet reactivity, and platelet morphol-
ogy was analysed under electron microscopy.
Results:
There was no difference in the proportion of active platelets
between the iPAH group and the control group at various sites. In the
iPAH group, the number of active platelets was significantly higher
in pulmonary artery compared to that of the femoral artery (
p
=
0.01).
By contrast, there was no difference in the number of active platelets
between various sites in patients with RHD with iPAH. Platelet reac-
tivity at the various sites did not differ significantly between iPAH
and RHD in the PAH groups. There was no significant difference
in platelet reactivity measured biochemically by collagen and ADP
between the pulmonary artery and the rest of the sites.
Conclusions:
We found an increased number of active platelets in the
pulmonary circulation compared to the systemic circulation on elec-
tron microscopy in iPAH patients. We found no difference biochemi-
cally in the level of platelet reactivity between the pulmonary and
systemic circulation. Patients with iPAH did not show significantly
higher platelet reactivity compared to patients with RHD with
moderate to severe PAH.
770: REVERSIBLE PULMONARY TRUNK BANDING. X:
WALL STRESS-ASSOCIATED ACTIVATION OF MYOCAR-
DIUM GLUCOSE-6-PHOSPHATE DEHYDROGENASE IS
NORMALISED BY INTERMITTENT SYSTOLIC OVER-
LOAD INYOUNG GOATS
Renato Assad, Acrisio Valente, Miriam Fonseca-Alaniz, Maria
Cristina Abduch, Gustavo Jose Silva, Fernanda Oliveira, Luiz Felipe
Moreira, Jose Krieger
Heart Institute, University of Sao Paulo School of Medicine, Sao
Paulo, Brazil
Division of Surgical Research, Heart Institute, University of Sao
Paulo School of Medicine, Sao Paulo, Brazil
Background
: Increased myocardial glucose-6-Phosphate dehydroge-
nase (G6PD) activity has been demonstrated in young goats submit-
ted to traditional pulmonary artery banding (PAB). This biochemical
alteration drives superoxide anion generation and elevates oxida-
tive stress by elevated G6PD-derived NADPH in the failing heart.
This study sought to assess the myocardial mechanics and kinetics
of G6PD activity during intermittent systolic overload of the sub-
pulmonary ventricle in a young animal model.
Methods:
Thirty young goats with comparable weights were sepa-
rated into five groups according to the study period duration (0,
24, 48, 72, and 96 hours). A 12-hour systolic overload of the right
ventricle (RV) was alternated with a 12-hour resting period with an
adjustable PAB. Systolic overload was adjusted to achieve a 0.7 RV/
aortic pressure ratio. Echocardiographic and haemodynamic evalua-
tions were performed every day postoperatively. After completing the
training programme of each group, the animals were humanely killed
for morphological and G6PD activity assessment.
Results:
A 130.8% increase occurred in the RV mass of the 96-hour
group, compared with the 0-hour group (
p
<
0.0001). Increased
RV volume/mass ratio and wall stress observed in the 24-, 48-, and
72-hour groups were associated with increased RV G6PD tissue
activity (Pearson correlation, 0.77 and 0.87;
p
=
0.05 and 0.03,
respectively). A full recovery of these parameters was observed in the
96-hour group, compared to baseline values. No significant changes
were observed in the G6PD activity of the ventricular septum and
left ventricle.
Conclusions:
G6PD tissue activity is associated with changes in
ventricular volume and RV wall stress. This study suggests that
intermittent systolic overload for sub-pulmonary ventricle retrain-
ing in young goats may improve the altered cardiac energy substrate
metabolism and decrease the formation of reactive oxygen species,
thus preventing cardiac deterioration post-PAB.
861: RIGHT VENTRICULAR MYOCARDIAL PERFOR-
MANCE INDEX IS PARADOXICALLY DECREASED WITH
SEVERE PRESSURE OVERLOAD CARDIAC HYPERTRO-
PHY INYOUNG RATS
Young Kuk Cho
1
, Jeong-Hyeon Ko
2
, Gwang Hyeon Eom
2
, Hwa Jin
Cho
1
, Kwang-Il Nam
3
, Hae In Jang
1
, Hyun Kook
2
, Jae Sook Ma
1
1
Department of Paediatrics, Chonnam National University Medical
School and Hospital, Republic of Korea
2
Department of Pharmacology, Chonnam National University
Medical School, Republic of Korea
3
Department of Anatomy, Chonnam National University Medical
School, Republic of Korea
Background
: Although the myocardial performance index (MPI) is
usually increased in the presence of RV dysfunction, debate contin-
ues over the correlation between right ventricular (RV) MPI and
functional derangement in patients with congenital heart disease
(CHD). To address this controversy, we took serial measurements of
the RV MPI during the development of RV dysfunction induced by
