Sarcoplasmic reticulum Ca2+uptake is not decreased in aorta from deoxycorticosterone acetate hypertensive rats: functional assessment with cyclopiazonic acid
| Autor: | L. M. Bendhack, R. C. Webb, O. Traub, Rita C. Tostes |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Male
Serotonin medicine.medical_specialty Indoles Phosphodiesterase Inhibitors Physiology Muscle Relaxation Aorta Thoracic Blood Pressure Calcium-Transporting ATPases In Vitro Techniques Muscle Smooth Vascular Rats Sprague-Dawley Vascular reactivity chemistry.chemical_compound Caffeine Physiology (medical) medicine.artery Internal medicine medicine Animals Enzyme Inhibitors Desoxycorticosterone Vascular contraction Pharmacology Ca2 uptake Aorta Endoplasmic reticulum General Medicine Rats Serotonin Receptor Agonists Surgery Sarcoplasmic Reticulum Endocrinology chemistry Hypertension Calcium Deoxycorticosterone acetate Cyclopiazonic acid Intracellular Muscle Contraction |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1205-7541 0008-4212 |
| DOI: | 10.1139/y95-212 |
| Popis: | Ca2+plays a major role in vascular contraction, and a defect in intracellular Ca2+regulation has been associated with increased vascular reactivity in hypertension. To test the hypothesis that the sarcoplasmic reticulum does not adequately buffer Ca2+in deoxycorticosterone acetate (DOCA) hypertension, contractile experiments were performed with a specific inhibitor of the sarcoplasmic reticulum Ca2+ATPase, cyclopiazonic acid (CPA). Contractile force in aortic strips from DOCA and control rats was measured, using standard muscle bath procedures, to evaluate (i) Ca2+handling, assessing caffeine and serotonin (5HT) induced contractions in Ca2+-free buffer and (ii) relaxation rate after 5HT washout. Contractile responses elicited with 5HT (3 × 10−6 mol/L) and caffeine (20 mmol/L) were greater in DOCA than in control arteries. CPA (1 × 10−7to 3 × 10−5 mol/L) reduced phasic contractions to 5HT and caffeine in DOCA and control aorta, and no differences in the IC50values were observed. Aortae from DOCA rats contracted when placed in normal buffer, subsequent to treatment with Ca2+-free buffer, but control aortae did not. CPA potentiated these responses in DOCA aorta and only caused a modest contraction in control aorta. CPA-induced contraction did not occur in Ca2+-free buffer, and it was inhibited by nifedipine (IC50 = 4 × 10−9 mol/L). The relaxation rate, after 5HT washout (3 × 10−6 mol/L), was increased in DOCA aorta (2.6 ± 0.3 min) compared with control (1.7 ± 0.2 min), and CPA (10−5 mol/L) increased the relaxation rate in both groups. The results support the hypothesis of defective Ca2+handling in DOCA hypertension. However, an increased Ca2+influx, and not a decreased buffering ability of the sarcoplasmic reticulum, contributes to the enhanced vascular reactivity observed in DOCA hypertension.Key words: vascular smooth muscle, intracellular calcium mobilization, caffeine, cyclopiazonic acid, sarcoplasmic reticulum, deoxycorticosterone (DOCA) hypertension. |
| Databáze: | OpenAIRE |
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