Activation of Cardiac Adenylyl Cyclase Expression Increases Function of the Failing Ischemic Heart in Mice
N. Chin Lai, PhD*, ,
Tong Tang, PhD*,,
Mei Hua Gao, PhD*,,
Miho Saito, MD*,
Toshiyuki Takahashi, MD, PhD*,
David M. Roth, MD, PhD, and
H. Kirk Hammond, MD*,,*
* Department of Medicine, University of California San Diego, San Diego, California
VA San Diego Healthcare System, University of California San Diego, San Diego, California
Department of Anesthesiology, University of California San Diego, San Diego, California.
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Figure 2 LV ACVI Content
The Western blot shows a marked increase in ACVI protein in LV samples from mice 5 weeks after activation of ACVI transgene expression (n = 8 for both groups). The graph summarizes data from Western blotting. Bars = mean values; error bars = 1 SE; number above bars = probability value (Student unpaired t test, 2-tailed). ACVI = adenylyl cyclase VI; LV= left ventricular.
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Figure 3 Contractile Function
The ESPVR was measured in intact mice 5 weeks after activation of ACVI expression in animals with severe CHF. Increased cardiac ACVI expression was associated with substantial increases in LV contractility as reflected in increased slope of the ESPVR. Cardiac loops, generated by altering loading conditions of the LV, are shown with the slope of the end-systolic pressure-volume point depicted. The graph below summarizes data from all animals. Numbers in bars denote animals studied. Bars = mean values; error bars = 1 SE; number above bars = probability value (Student unpaired t test, 2-tailed). CHF = congestive heart failure; ESPVR = end-systolic pressure-volume relationship; other abbreviations as in Figure 2.
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Figure 4 LV cAMP Production and PKA Activity
(Left) Increased ACVI expression was associated with increased cAMP generation in response to NKH477 (10 µM) stimulation of LV samples. Basal cAMP generation was not changed by ACVI expression. (Right) Increased cardiac ACVI expression was associated with increased PKA activity in LV samples. Numbers in bars = animals studied; bars = mean values; error bars = 1 SE; number above bars = probability value (Student unpaired t test, 2-tailed). cAMP = cyclic adenosine monophosphate; PKA = protein kinase A; other abbreviations as in Figure 2.
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Figure 5 LV cTnI Phosphorylation
The Western blot shows a marked increase in cTnI phosphorylation in LV samples from mice 5 weeks after activation of ACVI transgene expression. Summary of data from Western blotting is shown in the lower panel. Numbers in bars = animals studied; bars = mean values; error bars = 1 SE; number above bars = probability value (Student unpaired t test, 2-tailed). Abbreviations as in Figure 2.
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Figure 6 Apoptosis
Rates of LV apoptosis (TUNEL staining) were increased in both border and remote zones compared with the normal rate in murine LV of 50 TUNEL-positive nuclei per 100,000 cells (1). Activation of ACVI expression reduced the rate of apoptosis by about 50% in both regions. Numbers in bars = animals studied; bars = mean values; error bars = 1 SE; p value = probability value for gene effect (2-way analysis of variance). TUNEL = terminal 2'-deoxyuridine 5'-triphosphate nick-end labeling; other abbreviations as in Figure 2.
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