Heterogeneous Distribution Of beta-Adrenoceptors and Muscarinic Receptors In The Sinoatrial Node And Right Atrium Of The Dog
| Autor: | Yasuyuki Furukawa, Masamichi Hirose, Tokio Nakane, Fumio Kurogouchi, Shigetoshi Chiba, Yoichi Inada |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty Physiology Stimulation Dogs Physiology (medical) Internal medicine Receptors Adrenergic beta Muscarinic acetylcholine receptor medicine Animals Distribution (pharmacology) Heart Atria Receptor Sinoatrial Node Pharmacology Autonomic nerve Chemistry Sinoatrial node Myocardium Muscarinic acetylcholine receptor M2 Receptors Muscarinic Dissociation constant Endocrinology medicine.anatomical_structure Female |
| Zdroj: | Clinical and Experimental Pharmacology and Physiology. 29:666-672 |
| ISSN: | 1440-1681 0305-1870 |
| Popis: | SUMMARY 1. The pacemaker site is known to shift away from the sinoatrial (SA) node in response to autonomic stimuli. 2. To test whether the shifting of the impulse-initiation site that occurs during autonomic nerve stimulation can be explained by the spatial distributions of β-adrenoceptor and muscarinic receptors, we obtained densities (Bmax) and dissociation constants (Kd) for these receptors in three regions along the sulcus terminalis (the SA node itself and regions superior and inferior to it) and a region of the right atrial appendage in the dog. 3. The Bmax values for [125I]-iodocyanopindolol binding to β-adrenoceptors were not different among the four regions. The Bmax value for [3H]-quinuclidinyl benzilate binding to muscarinic receptors was significantly higher in the SA node area than in any other region (P < 0.01), although there was no difference among the other three regions. 4. For each receptor, Kd values were similar among the four regions. 5. These results suggest that spatial variations in the densities of β-adrenoceptors and muscarinic receptors are not important for shifting the impulse-initiation site and that other factors, such as non-uniform innervation by autonomic nerve fibres, may be mainly responsible for the pacemaker shift induced by autonomic nerve stimulation. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|