John Patrick Headrick

Cardiac and coronary function in the Langendorff-perfused mouse heart model (2008)

Reichelt, Melissa Elizabeth, Willems, Laura, Hack, Benjamin A., Peart, Jason Nigel John, Headrick, John Patrick

The Langendorff mouse heart model is widely employed in studies of myocardial function and responses to injury (e.g. ischaemia). Nonetheless, marked variability exists in its preparation and...

Activation of kappa-opioid receptors at reperfusion affords cardioprotection in both rat and mouse hearts. (2008)

Peart, Jason Nigel John, Gross, Eric R., Reichelt, Melissa Elizabeth, Hsu, Anna, Headrick, John Patrick, Gross, Garrett J.

The temporal properties of kappa-opioid receptor (κ-OR) mediated cardioprotection are less well characterised than delta-opioid receptor (δ-OR) responses. This study was aimed at delineating the...

Cardiac and coronary function in the Langendorff-perfused mouse heart model (2008)

Reichelt, Melissa Elizabeth, Willems, Laura, Hack, Benjamin A., Peart, Jason Nigel John, Headrick, John Patrick

The Langendorff mouse heart model is widely employed in studies of myocardial function and responses to injury (e.g. ischaemia). Nonetheless, marked variability exists in its preparation and...

Age-associated shifts in cardiac gene transcription and transcriptional responses to ischemic stress (2006)

Ashton, Kevin John, Willems, Laura, Holmgren, Kirsty, Ferreira, Linda Anne, Headrick, John Patrick

Aged hearts exhibit reduced tolerance to ischemia-reperfusion, together with altered structure and post-ischemic remodelling. The molecular bases of such changes are unclear. Using cDNA microarrays...

Adenosine receptor-mediated coronary vascular protection in post-ischemic mouse heart (2006)

Zatta, Amanda Jane, Matherne, G. Paul, Headrick, John Patrick

This study evaluated the ability of A1 and A3 adenosine receptor (AR) agonism, and A1, A2A, A2B and A3AR antagonism (revealing "intrinsic" responses), to modify post-ischemic coronary dysfunction in...

Effects of adenosine deaminase and A1 receptor deficiency in normoxic and ischaemic mouse hearts (2006)

Willems, Laura, Reichelt, Melissa Elizabeth, Molina, Jose G, Sun, Chun-Xiao, Chunn, Janci L, Ashton, Kevin John, ...

OBJECTIVE: Adenosine deaminase (ADA) may be multifunctional, regulating adenosine levels and adenosine receptor (AR) agonism, and potentially modifying AR functionality. Herein we assess effects of...

Oxidant Stress and Damage in Post-Ischemic Mouse Hearts: Effects of Adenosine (2006)

Hack, Benjamin Daniel Noel, Witting, Paul K, Rayner, Benjamin S., Stocker, Roland, Headrick, John Patrick

Despite the general understanding that ischemia-reperfusion (I/R) promotes oxidant stress, specific contributions of oxidant stress or damage to myocardial I/R injury remain poorly defined. Moreover,...

Protecting murine hearts from ischaemia-reperfusion using selective inhibitors of adenosine metabolism (2005)

Willems, Laura, Headrick, John Patrick

1. By selectively modifying adenosine metabolism via adenosine deaminase or adenosine kinase inhibitors, it may be possible to enhance the receptor-mediated protective actions of adenosine in a site-...

A3 adenosine receptor-mediated protection of the ischemic heart (2005)

Headrick, John Patrick, Peart, Jason Nigel John

The A3 adenosine receptor (A3AR) is attributed with multiple beneficial actions in ischemic–reperfused myocardium, including modulation of oncotic and apoptotic cell death and enhancement of...

Postconditioning reduces infarct size via adenosine receptor activation by endogenous adenosine (2005)

Kin, Hajime, Zatta, Amanda J., Lofye, Mark T., Amerson, Bradley S., Halkos, Michael E., Kerendi, Faraz, ...

Objective This study tested the hypothesis that brief cycles of iterative ischemia–reperfusion at onset of reperfusion (termed “postconditioning”, post-con) delays washout of intravascular...

Effects of dietary selenium on glutathione peroxidase and thioredoxin reductase activity and recovery from cardiac ischemia-reperfusion (2004)

Venardos, Kylie, Harrison, Glenn, Headrick, John Patrick, Perkins, Anthony Vincent

Glutathione peroxidase and thioredoxin reductase are selenocysteine-dependent enzymes that protect against oxidative injury. This study examined the effects of dietary selenium on the activity of...

Effects of A1 adenosine receptor overexpression on normoxic and post-ischemic gene expression (2003)

Ashton, Kevin John, Holmgren, Kirsty, Peart, Jason Nigel John, Lankford, Amy R., Matherne, G. Paul, Grimmond, Sean, ...

Objectives: To identify potential molecular genetic determinants of cardiovascular ischemic tolerance in wild-type and transgenic hearts overexpressing A1 adenosine receptors (A1ARs). Methods: cDNA...

Pyruvate-dependent preconditioning and cardioprotection in murine myocardium (2003)

Zatta, Amanda Jane, Hack, Benjamin Daniel Noel, Headrick, John Patrick

1. Whether pyruvate inhibits or can actually initiate myocardial preconditioning is unclear and whether pyruvate provides protection via its action as a 'cosubstrate' with glucose or via alternative...

Ischaemic tolerance in aged mouse myocardium: the role of adenosine and effects of A1 adenosine receptor overexpression (2003)

Headrick, John Patrick, Willems, Laura, Ashton, Kevin John, Holmgren, Kirsty, Peart, Jason Nigel John, Matherne, G. Paul

The genesis of the ischaemia intolerant phenotype in aged myocardium is poorly understood. We tested the hypothesis that impaired adenosine-mediated protection contributes to ischaemic intolerance,...

Adenosine-mediated early preconditioning in mouse: protective signaling and concentration dependent effects (2003)

Peart, Jason Nigel John, Headrick, John Patrick

Objective: ±1-Adrenergic receptors (ARs) are known mediators of a positive inotropy in the heart, which may play even more important roles in heart disease. Due to a lack of sufficiently selective...

Aging-related changes in myocardial purine metabolism and ischemic tolerance (2003)

Willems, Laura, Garnham, Bronwyn Gaye, Headrick, John Patrick

Impaired tolerance to ischemia-reperfusion in older hearts may stem in part from alterations in purine catabolism, impacting on maintenance of energy state and protective signaling via extracellular...

Coronary function and adenosine receptor-mediated responses in ischemic reperfused mouse heart (2002)

Zatta, Amanda Jane, Willems, Laura, Headrick, John Patrick

Objectives: To assess the impact of ischemia-reperfusion (I/R) on coronary function, and the role of endogenous adenosine in modifying post-ischemic vascular function in asanguinous hearts. Methods:...

Effects of A3 adenosine receptor activation and gene knock-out in ischemic-reperfused mouse heart (2002)

Harrison, Glenn, Cerniway, Rachael J, Peart, Jason Nigel John, Berr, Stuart S, Ashton, Kevin John, Regan, Sara, ...

Objectives: To characterize effects of A3 adenosine receptor (A3AR) activation and gene knock-out on responses to ischemia-reperfusion in mouse heart. Methods: Perfused hearts from wild-type and A3AR...

Cardioprotection with adenosine metabolism inhibitors in ischemic-reperfused mouse heart (2001)

Peart, Jason Nigel John, Matherne, Paul, Cerniway, Rachel, Headrick, John Patrick

Objectives: To characterize the anti-ischemic' effects of adenosine metabolism inhibition in ischemic reperfused myocardium. Methods: Perfused C57/B16 mouse hearts were subjected to 20 min ischemia...

5'-Adenosine monophosphate and adenosine metabolism, and adenosine responses in mouse, rat and guinea pig heart (2001)

Headrick, John Patrick, Peart, Jason Nigel John, Hack, Benjamin Daniel Noel, Garnham, Bronwyn Gaye, Matherne, G Paul

We examined myocardial 52-adenosine monophosphate (52-AMP) catabolism, adenosine salvage and adenosine responses in perfused guinea pig, rat and mouse heart. MV2 increased from 71±8 ¼l O2/min per g...

Acute but not chronic caffeine impairs functional responses to ischaemia-reperfusion in rat isolated perfused heart. (2001)

Rose'Meyer, Roselyn, Headrick, John Patrick, Peart, Jason Nigel John, Harrison, Glenn, Garnham, Bronwyn Gaye, Willis, Roger

1. The effect of acute (50 ¼mol/L) and chronic (0.06% in drinking water for 14 days) caffeine on the response to ischaemia reperfusion was studied in Wistar rat isolated perfused hearts. 2. Neither...

Chronotropic and vasodilatory responses to adenosine and B-adrenoceptor activation in mouse hear: effects of adenosine A1 receptor overexpression (2000)

Headrick, John Patrick, Gauthier, NS, Morrison, RR, Matherne, GP

1. Chronotropic and vasodilatory effects of adenosine receptor activation with 2-chloroadenosine (2-ClAdo) and ²-adrenoceptor activation with isoproterenol were studied in wild-type murine hearts...