P2 Antagonist Ppads Attenuates Responses of Thin Fiber Afferents to Static Contraction and Tendon Stretch.
From: Division of Cardiovascular Medicine, TB 172, One Shields Dr., University of California, Davis, California 95616, USA. aekindig@ucdavis.edu
American journal of physiology. Heart and circulatory physiology
- Publish Date: Mar 2006
- ISSN: 0363-6135
- Volume: 290
- Issue: 3
- Pages: H1214-9
- Medium: Print
- Language: English
- Citation (JAMA): Kindig Angela E, Hayes Shawn G, Hanna Ramy L, et al. P2 Antagonist Ppads Attenuates Responses of Thin Fiber Afferents to Static Contraction and Tendon Stretch.. Am. J. Physiol. Heart Circ. Physiol. Mar 2006;290:H1214-9
Abstract
Injection into the arterial supply of skeletal muscle of pyridoxal phosphate-6-azophenyl-2’,4’-disulfonic acid (PPADS), a P2 receptor antagonist, has been shown previously to attenuate the reflex pressor responses to both static contraction and to tendon stretch. In decerebrated cats, we tested the hypothesis that PPADS attenuated the responses of groups III and IV muscle afferents to static contraction as well as to tendon stretch. We found that injection of PPADS (10 mg/kg) into the popliteal artery attenuated the responses of both group III (n = 16 cats) and group IV afferents (n = 14 cats) to static contraction. Specifically, static contraction before PPADS injection increased the discharge rate of the group III afferents from 0.1 +/- 0.05 to 1.6 +/- 0.5 impulses/s, whereas contraction after PPADS injection increased the discharge of the group III afferents from 0.2 +/- 0.1 to only 1.0 +/- 0.5 impulses/s (P < 0.05). Likewise, static contraction before PPADS injection increased the discharge rate of the group IV afferents from 0.3 +/- 0.1 to 1.0 +/- 0.3 impulses/s, whereas contraction after PPADS injection increased the discharge of the group IV afferents from 0.2 +/- 0.1 to only 0.3 +/- 0.1 impulses/s (P < 0.05). In addition, PPADS significantly attenuated the responses of group III afferents to tendon stretch but had no effect on the responses of group IV afferents. Our findings suggest that both groups III and IV afferents are responsible for evoking the purinergic component of the exercise pressor reflex, whereas only group III afferents are responsible for evoking the purinergic component of the muscle mechanoreflex that is evoked by tendon stretch.
Mesh Headings (Keywords): Afferent Pathways, Animals, Cats, Muscle Contraction, Muscle, Skeletal, Nerve Fibers, Platelet Aggregation Inhibitors, Pyridoxal Phosphate, Receptors, Purinergic P2, Reflex, Stretch, Tendons
Check for Full Text / PubMed Unique Identifier (PMID): 16258028
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