Breaking News
February 22, 2019 - Biologist uses new grant to find ways to eliminate schistosomiasis
February 22, 2019 - Bag-mask ventilation to help patients breathe during intubation prevents complications
February 22, 2019 - AbbVie Announces New Drug Application Accepted for Priority Review by FDA for Upadacitinib for Treatment of Moderate to Severe Rheumatoid Arthritis
February 22, 2019 - Nature versus nurture and addiction
February 22, 2019 - New website connects researchers with data experts, resources | News Center
February 22, 2019 - Today’s Concerns About Drug Prices Echo The Past
February 22, 2019 - CT and Doppler equipment have low accuracy in detecting cerebral vasospasm and ischemia
February 22, 2019 - Study finds out similarity in function between healthy retina cell and tumor cell
February 22, 2019 - CWRU awarded NIH grant to identify effective treatments for intimate partner violence
February 22, 2019 - Oncotype DX Not Cost-Effective for Low-Risk Breast Cancer
February 22, 2019 - Scientists discover new type of immune cells that are essential for forming heart valves
February 22, 2019 - Talk About Déjà Vu: Senators Set To Re-Enact Drug Price Hearing Of 60 Years Ago
February 22, 2019 - Genetic defect linked to pediatric liver disease identified
February 22, 2019 - New cellular atlas could provide a deeper insight into blinding diseases
February 22, 2019 - Growing number of cancer survivors, fewer providers point to challenge in meeting care needs
February 22, 2019 - Innovative compound offers a new therapeutic approach to treat multiple sclerosis
February 22, 2019 - $1.5 million grant to develop opioid treatment program for jail detainees
February 22, 2019 - FDA’s new proposed rule would update regulatory requirements for sunscreen products in the U.S
February 22, 2019 - Most Hip, Knee Replacements Last Decades, Study Finds
February 22, 2019 - Wellness problems prevalent among ob-gyn residents
February 22, 2019 - In the Spotlight: “The world is your oyster in geriatrics”
February 22, 2019 - Successful testing of multi-organ “human-on-a-chip” could replace animals as test subjects
February 22, 2019 - Analysis of cervical precancer shows decline in two strains of HPV
February 22, 2019 - Sugary stent eases suturing of blood vessels
February 22, 2019 - From surgery to psychiatry: A medical student reevaluates his motivations
February 22, 2019 - Is New App From Feds Your Answer To Navigating Medicare Coverage? Yes And No
February 22, 2019 - New pacemakers powered by heartbeats could reduce need for surgery
February 22, 2019 - The United States records highest drug overdose death rates
February 22, 2019 - Phase 1 data reinforce safety profile of new drug for treating Duchenne muscular dystrophy
February 22, 2019 - Vitamin D supplementation less effective in the presence of obesity, shows study
February 22, 2019 - CPRIT awards nearly $20 million to The University of Texas MD Anderson Cancer Center
February 22, 2019 - Sarepta Announces FDA Acceptance of Golodirsen (SRP-4053) New Drug Application for Patients with Duchenne Muscular Dystrophy Amenable to Skipping Exon 53
February 22, 2019 - An institutional effort to reduce the amount of opioids prescribed following lumbar surgery
February 22, 2019 - Family-history-based models perform better than non-family-history based models
February 22, 2019 - Failure to take statins leads to higher mortality rates | News Center
February 22, 2019 - New study explains why some patients report phantom sensations after limb amputation
February 22, 2019 - First motor-controlled heart valves implanted by Mainz University Medical Center
February 22, 2019 - Novel preclinical model mimics persistent interneuron loss seen in preterm infants
February 22, 2019 - Global health burden of glaucoma has increased, study reveals
February 22, 2019 - A holistic approach key to minimize treatment complexity in patients with interstitial lung disease
February 22, 2019 - 1 in 10 middle-aged Chinese adults are at high risk for heart disease, finds study
February 22, 2019 - More than half a million breast cancer patient’s lives saved by improvements in treatment
February 22, 2019 - Study finds no evidence that tougher policies prevent teenage cannabis use
February 22, 2019 - New blood test detects genetic disorders in fetuses
February 22, 2019 - Lower Self-Perception Observed in Children With Amblyopia
February 22, 2019 - Up to 15 percent of children have sleep apnea, yet 90 percent go undiagnosed
February 22, 2019 - Rare pulmonary defect prompts parents’ nationwide search for answers | News Center
February 22, 2019 - Lesbian and bisexual women at greater risk of being overweight, study finds
February 22, 2019 - UQ research may explain why vitamin D is essential for brain health
February 22, 2019 - Heart Attacks Rising Among Younger Women
February 22, 2019 - How your smartphone is affecting your relationship
February 22, 2019 - Orthopaedic surgeon receives prestigious award, $10 million grant | News Center
February 22, 2019 - New sepsis test could save thousands of lives
February 22, 2019 - Cervical cancer could be eradicated by 2100
February 21, 2019 - Sustained smoking cessation can lower risk of seropositive RA
February 21, 2019 - Thousands with chronic UTIs are not receiving the treatment they need
February 21, 2019 - Are teens getting high on social media? The surprising study seeking the pot-Instagram link
February 21, 2019 - Stanford expands biobank services | News Center
February 21, 2019 - Scientists identify link between drinking contexts and early onset intoxication among adolescents
February 21, 2019 - Strong social support may reduce cardiovascular disease risk in postmenopausal women
February 21, 2019 - Rapid expansion of interventions could prevent up to 13 million cases of cervical cancer within 50 years
February 21, 2019 - Motif Bio Receives Complete Response Letter From The FDA
February 21, 2019 - Researchers map previously unknown disease in children
February 21, 2019 - A skeptical look at popular diets: Going gluten-free
February 21, 2019 - Podcast: KHN’s ‘What The Health?’ How Safe Are Your Supplements?
February 21, 2019 - Factors associated with increased risk of developing surgical site infections
February 21, 2019 - Anticipatory signals in eye movements can help measure attentive capacity, learning with greater precision
February 21, 2019 - Study explores daily exposure to indoor air pollutants
February 21, 2019 - Evening exercise does not negatively affect sleep, may also reduce hunger
February 21, 2019 - Artificial intelligence technique can be used to identify alcohol misuse in trauma setting
February 21, 2019 - Overweight, obesity in adolescence associated with increased risk of renal cancer later in life
February 21, 2019 - BGU develops new AI platform for monitoring and predicting ALS progression
February 21, 2019 - Researchers discover a new promising target to improve HIV vaccines
February 21, 2019 - Brief Anesthesia in Infancy Does Not Mar Neurodevelopment
February 21, 2019 - Gaming system helps with autism diagnosis
February 21, 2019 - Heart Disease: Six Things Women Should Know
February 21, 2019 - More States Say Doctors Must Offer Overdose Reversal Drug Along With Opioids
February 21, 2019 - Researchers explore case studies focused on industries that kill more people than employed
February 21, 2019 - Only half of GP practice buildings are fit for purpose
February 21, 2019 - Intense exercise, fasting and hormones can enhance waste-protein removal, study shows
Drug in clinical trials for Parkinson’s disease offers hope for treating heart failure

Drug in clinical trials for Parkinson’s disease offers hope for treating heart failure

image_pdfDownload PDFimage_print

A drug currently in clinical trials for treating symptoms of Parkinson’s disease may someday have value for treating heart failure, according to results of early animal studies by Johns Hopkins Medicine researchers.

The drug, a member of a class of compounds known as phosphodiesterase (PDE) type I inhibitors, shows promising effects on dog and rabbit hearts, as well as on isolated rabbit heart cells, most notably an increase in the strength of the heart muscle’s contractions, the researchers say.

Human heart failure is a chronic condition often marked by weakening of the heart muscle and its subsequent failure to pump enough blood. Currently, dozens of drugs are available to treat or manage heart failure symptoms, but drugs that improve the strength of the heart muscle’s contractions, such as dobutamine, carry the risk of dangerous complications such as developing an irregular heartbeat.

However, in their study, described in a report published in the journal Circulation on July 20, the Johns Hopkins researchers demonstrate that the new compound works differently than current drugs, suggesting its use may be a safer way to increase heart contraction strength.

Heart failure affects about 5.7 million U.S. adults, according to the Centers for Disease Control and Prevention, and contributes to an estimated one in nine deaths. Standard treatment includes diuretics that increase urine production to keep the heart from becoming enlarged; angiotensin-converting enzyme (ACE) inhibitors that lower blood pressure and reduce the workload on the heart; and beta blockers that protect against heart damage from high levels of the stress hormone adrenaline that are common with heart failure, and that help reduce the heart’s workload. There is no cure.

“Our results are intriguing because so far it’s been largely uncharted territory to come up with a way of increasing contractility that doesn’t ultimately hurt patients,” says David Kass, M.D., the Abraham and Virginia Weiss Professor of Cardiology at the Johns Hopkins University School of Medicine and principal investigator of the study.

The drug explored in the new study, ITI-214, inhibits the enzyme PDE1, which is part of the larger phosphodiesterase (PDE) family of over 100 such proteins. All PDEs work by breaking down one or both of two molecules: cAMP and cGMP, each of which serve as molecular messengers inside cells. Each PDE has very specific features, including the type of cell they exist in and their location inside that cell, allowing them to adjust cAMP and/or cGMP very precisely.

PDE inhibitors work by stopping the breakdown of cAMP and cGMP, causing these molecules to build up so they can influence proteins to alter the cell. In heart disease, PDE activity can limit the beneficial effects of cAMP or cGMP, so inhibitors have the potential to act as a therapy.

In mice, Kass notes, PDE1 inhibitors had been reported to shrink abnormally thick heart muscle caused by high blood pressure and dilate blood vessels. However, in mice the heart mostly has a different form of the PDE1 enzyme than found in humans, so PDE1 inhibitors likely affect mice differently than humans.

Dogs and rabbits, which this research focused on, have a PDE1 composition more similar to humans, Kass says.

For their experiments, the researchers used six dogs surgically outfitted with sensors and heart pacemakers, and tested ITI-214’s effects on them before and after inducing heart failure by running the pacemaker rapidly for approximately three weeks. The drug was tested at different doses, both orally and intravenously. The dogs were given at least a day between tests.

When given at an oral dose of 10 milligrams for every kilograms via a peanut butter-covered pill, ITI-214 increased the amount of blood pumped out by the heart each minute by 50 percent in the healthy hearts and by 32 percent in the failing hearts. It did this, Kass says, by increasing the strength of the heart’s contractions by almost 30 percent and by dilating the blood vessels. Intravenous administration of the drug resulted in similar, but more rapid, effects.

“We were pretty agnostic about what we would find and didn’t necessarily expect anything that novel,” says Kass. “To my knowledge, no study had reported increased heart contraction strength from a PDE1 inhibition before. But then, all of the prior studies where this might have been tested had used mice, and we knew that a different PDE1 form was found in larger mammals and humans. So, we just had to try it, and the results were very interesting.”

In healthy dogs, Kass cautions, the drug also raised their heart rate by approximately 40 beats per minute on average, which can be dangerous for heart failure patients. However, the dogs with failing hearts had no significant difference in heart rate before and after the drug was given.

Even with these promising results, there was a major concern. Other heart failure drugs designed to strengthen heart contractions have potentially fatal complications, such as developing wildly irregular heartbeats. Inhibitors of a different PDE, PDE3, including amrinone and milrinone, are especially infamous for this.

“This was the boogeyman in the room,” says Kass. “The new drug produced many of the same heart and artery changes that PDE3 inhibitors do, so we naturally worried whether it worked in a similar way and might also have complications. So we tested them side by side.”

When they compared the effects of ITI-214 to a PDE3 inhibitor in isolated muscle cells from 13 rabbit hearts, the way the two drugs acted looked different.

One of the major ways that PDE3 inhibitors are thought to work is by increasing the amount of calcium inside the muscle cell, which triggers key proteins to exert more force on the cell, and causes the cell to contract more strongly.

As expected, when the researchers applied a PDE3 inhibitor to the heart cells, calcium levels rose and the cells contracted more strongly than without the inhibitor.

By itself, inhibiting PDE1 had no effect on the muscle cells, but the researchers thought this might be because PDE1 activity is too low in a resting cell. So they used a drug to first slightly increase cAMP levels, and this increased PDE1 activity enough for them to observe ITI-214’s effects.

With the added drug, ITI-214 caused the cell to contract more strongly. However, the cell’s calcium levels didn’t rise, strongly indicating that ITI-214 increases muscle contractions through a different mechanism than the PDE3 inhibitors.

“Our results show that inhibiting PDE1 produces different changes than blocking PDE3, and so we hope that we can bypass the calcium-mediated and potentially deadly arrhythmias that have plagued PDE3 inhibitors,” says Grace Kim, a lead co-author and a postdoctoral fellow in Kass’ lab. “We are anticipating similar positive benefits on heart function but with much less toxicity.”

Kass says ITI-214 also appears to function differently than dobutamine, which strengthens heart contractions in people with heart failure but also can cause fatal irregular heart rhythms. Dobutamine works by stimulating the beta adrenergic system, the same system that is activated by adrenaline. Dobutamine acts on the same pool of messenger molecules that increase the cAMP that PDE3 degrades, so its heart effects are similar to those of a PDE3 inhibitor.

When the researchers blocked the beta adrenergic receptors in 11 healthy, anesthetized rabbits and then applied ITI-214, all of the effects–except for its impact on heart rate–remained. If ITI-214 were acting through the beta adrenergic system, blocking the receptors should have blocked its actions.

Instead, it appears the drug might be working on cAMP generated by a different signaling system in the heart that uses adenosine. When the researchers used a drug to block receptors in the adenosine system in a separate set of seven anesthetized rabbits, all of the effects of the drug, including increased heart rate, were eliminated.

Other studies have demonstrated that the adenosine pathway can have protective effects on the heart, Kass says. In the same issue of Circulation, other investigators at the University of Rochester also found that PDE1 controls the adenosine pathway, and that inhibiting PDE1 could protect the heart from toxicity of some cancer drugs.

ITI-214 is now in early clinical trials and is being tested in heart failure patients at Johns Hopkins Medicine and Duke University. It has already passed phase 1 safety trials in healthy individuals.

Source:

https://www.hopkinsmedicine.org/news/media/releases/drug_now_in_clinical_trials_for_parkinsons_strengthens_heart_contractions_in_animals

Tagged with:

About author

Related Articles