Patients with heart failure (HF) typically demonstrate a reduced work capacity when compared to normal individuals. This reduced work capacity has been attributed, in park to the early onset muscular fatigue and has been correlated with reductions in blood flow to working skeletal muscle. The primary objective of this proposal is to identify the factors contributing to the reductions in skeletal muscle blood flow in the HF state. Towards this objective, a surgically induced myocardial infarction (MI) or a sham operation (SHAM) will be performed on adult female Wistar rats. Following 6 weeks of recovery, the extent of LV dysfunction and HF produced will be determined by measuring LV and RV pressures in vivo in the awake resting animal. The vascular transport capacity (VTC) of the hind limb musculature will then be assessed using the isolated hindquarters perfusion technique. The different components of the VTC, the vascular flow capacity and capillary exchange capacity, will be determined in NU rats and analyzed as a function of LV infarct size (small, medium, large and extensive infarcts) and compared to both components in SHAM rats. In addition, the flow component of the VTC of the hind limb musculature will be examined in individual muscles with radiolabeled microspheres. This experimental approach will allow us to determine if the decrement in the VTC of the hind limb musculature of MI rats becomes greater as the size of the infarct becomes larger, the amount of LV dysfunction worsens and as the degree of HF progresses from the compensated to the decompensated congestive state. We will also determine whether the formation of interstitial edema is one of the mechanisms responsible for limiting flow in the skeletal muscle of MI rats by reducing the amount of fluid retained in the extravascular space of rats with diuretic therapy and by examining the effects of this intervention on the VTC of the hind limb musculature. Finally, we will determine whether endurance exercise training can ameliorate the decrements in the VTC of the hind limb musculature of MI rats. Altogether, these studies will corroborate our preliminary studies where decrements in the vascular flow capacity of hind limb musculature of rats with a large MI were found. They will provide a better understanding of the mechanisms involved that produce the decrements in skeletal muscle blood flow in the BF state and they will prove useful in the development of clinical strategies for mating this debilitating disease.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
1R01AG011535-01
Application #
3123446
Study Section
Respiratory and Applied Physiology Study Section (RAP)
Project Start
1992-09-30
Project End
1993-08-31
Budget Start
1992-09-30
Budget End
1993-08-31
Support Year
1
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Pennsylvania State University
Department
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Copp, Steven W; Hirai, Daniel M; Hageman, K Sue et al. (2010) Nitric oxide synthase inhibition during treadmill exercise reveals fiber-type specific vascular control in the rat hindlimb. Am J Physiol Regul Integr Comp Physiol 298:R478-85
Musch, T I; McAllister, R M; Symons, J D et al. (2001) Effects of nitric oxide synthase inhibition on vascular conductance during high speed treadmill exercise in rats. Exp Physiol 86:749-57
Zhang, X Q; Zhang, L Q; Palmer, B M et al. (2001) Sprint training shortens prolonged action potential duration in postinfarction rat myocyte: mechanisms. J Appl Physiol 90:1720-8
Mattson, J P; Ross, C R; Kilgore, J L et al. (2000) Induction of mitochondrial stress proteins following treadmill running. Med Sci Sports Exerc 32:365-9
Kindig, C A; Musch, T I; Basaraba, R J et al. (1999) Impaired capillary hemodynamics in skeletal muscle of rats in chronic heart failure. J Appl Physiol 87:652-60
Symons, J D; Stebbins, C L; Musch, T I (1999) Interactions between angiotensin II and nitric oxide during exercise in normal and heart failure rats. J Appl Physiol 87:574-81
Zhang, X Q; Musch, T I; Zelis, R et al. (1999) Effects of impaired Ca2+ homeostasis on contraction in postinfarction myocytes. J Appl Physiol 86:943-50
Symons, J D; Musch, T I; Hageman, K S et al. (1999) Regional blood flow responses to acute ANG II infusion: effects of nitric oxide synthase inhibition. J Cardiovasc Pharmacol 34:116-23
Xu, L; Poole, D C; Musch, T I (1998) Effect of heart failure on muscle capillary geometry: implications for 02 exchange. Med Sci Sports Exerc 30:1230-7
Poole, D C; Musch, T I; Kindig, C A (1997) In vivo microvascular structural and functional consequences of muscle length changes. Am J Physiol 272:H2107-14

Showing the most recent 10 out of 19 publications