Altered Calcium Handling in Peripheral Nerve Terminals and Blood Vessels in Spontaneously Hypertensive Rats
| Autor: | Yumi Koike, Naomi Iwane, Takuzo Hano |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
medicine.medical_specialty Contraction (grammar) Voltage-dependent calcium channel Ryanodine receptor medicine.drug_class Chemistry chemistry.chemical_element Stimulation Calcium channel blocker Calcium musculoskeletal system Calcium in biology Clonidine 03 medical and health sciences 030104 developmental biology Endocrinology Internal medicine cardiovascular system medicine circulatory and respiratory physiology medicine.drug |
| Zdroj: | Health. :317-322 |
| ISSN: | 1949-5005 1949-4998 |
| DOI: | 10.4236/health.2017.92022 |
| Popis: | The present study was designed to clarify the roles of N-type and P/Q-type calcium channels in the increased sympathetic activity of spontaneously hypertensive rats (SHR/Izm). We also tested in SHR/Izm the contribution to increased vascular tone of α1A adrenoceptor-linked L-type calcium channels and α1B receptor-mediated calcium mobilization from the sarcoplasmic reticulum. Methods: Six-week-old SHR/Izm and Wistar-Kyoto rats (WKY/Izm) were used. A superior mesenteric arterial preparation was electrically stimulated before and after treatment with ω-conotoxin GVIa (N-type calcium channel blocker [CgTX]) and ω-agatoxinIVa (P/Q-type calcium channel blocker [AgaTX]). Pressor response to norepinephrine was measured before and after treatment with the α1A blocker WB-4101 and the α1B blocker chloroethyl clonidine (CEC). To determine the intracellular calcium store size, the effects of ryanodine on pressor response and caffeine-induced vascular contraction were also tested. Results: Norepinephrine overflow evoked by electrical stimulation was increased in SHR/Izm. CgTX but not AgaTX suppressed the increased NE overflow in SHR/Izm. WB-4101 suppressed the pressor response to norepinephrine in SHR/Izm but not WKY/Izm rats. CEC had no effects on pressor response to norepinephrine in both types of rats. Caffeine-induced contraction to a high potassium-induced maximal contraction ratio was reduced in SHR/Izm. The effect of ryanodine on pressor response was reduced in SHR/Izm. Conclusion: N-type calcium channels but not P/Q-type calcium channels play an important role in the increased sympathetic tone in SHR/ Izm. Although α1A adrenoceptor-linked L-type calcium channels contribute to the increased vascular tone, the intracellular calcium store size was reduced in SHR/Izm. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|