We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
ET<sub>B2</sub> Receptor Subtype Stimulation Relaxes the Iris Sphincter Muscle.
- Authors
Rocha-Sousa, A.; Saraiva, J.; Amaral, M.; Alves-Faria, P.; Falcão-Reis, F.; Leite-Moreira, A. F.
- Abstract
Effects of ETB receptor stimulation and its subcellular pathways were evaluated in carbachol pre-contracted rabbit iris sphincter muscles (n=51). ETB stimulation with sarafotoxin (SRTX-c; 10-10-10-6 M) was tested in the absence (n=7) or presence of 10-5 M of: BQ-788 (ETB2 receptor antagonist; n=6), L-NA (NOS inhibitor; n=7) or indomethacin (cyclooxygenase inhibitor; n=10). Effects of ETB stimulation by endothelin-1 (ET-1; 10-10- 10-7 M) in the presence of an ETA receptor antagonist (BQ-123; 10-5 M; n=7) and of ETB1 stimulation by IRL-1620 (10-10-10-7 M; n=7) were also tested. Finally, the effects of SRTX-c (10-9-10-7 M) in electric field stimulation (EFS) contraction were evaluated (n=7). ETB receptor stimulation by SRTX-c or ET-1 in presence of BQ-123 promoted a concentration-dependent relaxation of the rabbit iris sphincter muscle by 10.8±2.0 % and 9.4±1.8 %, respectively. This effect was blocked by BQ-788 (-2.3±2.0 %), L-NA (4.5±2.3 %) or indomethacin (2.3±2.9 %). Selective ETB1 stimulation by IRL-1620 did not relax the iris sphincter muscle (0.9±5.4 %). EFS elicited contraction was not altered by SRTX-c. In conclusion, ETB receptor stimulation relaxes the carbachol precontracted iris sphincter muscle, an effect that is mediated by the ETB2 receptor subtype, through NO and the release of prostaglandins.
- Subjects
SPHINCTERS; MUSCLE contraction; LABORATORY rabbits; ANIMAL models in research; INDOMETHACIN; CYCLOOXYGENASE 2 inhibitors; PROSTAGLANDIN synthesis
- Publication
Physiological Research, 2009, Vol 58, Issue 6, p835
- ISSN
0862-8408
- Publication type
Article