High blood pressure. Causes, symptoms, treatments

A stepwise approach in the management of chronic spontaneous urticaria in children.

2017-05-31

Previous studies reported the existence of both D1- and D2-like receptors in the cortical collecting duct (CCD). However, especially with regard to natriuresis, it remains controversial. In the present study, rabbit CCD was perfused to characterize the receptor subtypes responsible for the tubular actions. Basolateral dopamine (DA) induced a dose-dependent depolarization of transepithelial voltage. Basolateral domperidone, a D2-like receptor antagonist, abolished depolarization, whereas SKF-81297, a D1-like receptor agonist, showed no significant change. In addition, bromocriptine, a D2-like receptor agonist, also caused depolarization, whereas SKF-81297, a D1-like receptor agonist, did not depolarize significantly. Moreover, RBI-257, a D4-specific antagonist, reversed the basolateral DA-induced depolarization. In contrast to the basolateral side, luminal DA caused depolarization via a D1-like receptor; however the change was less than that for basolateral DA. For further evaluation, 22Na+ flux (J(Na)) was measured to confirm the effect of DA on Na+ transport. Basolateral DA also caused a suppression of J(Na), and this reaction was abolished by domperidone. These results suggested that the basolateral D2-like receptor is mainly responsible for the natriuretic action of DA in rabbit CCD.

Patients receiving outpatient chemotherapy, without cisplatin, were randomised to receive four doses of either domperidone 60 mg or prochlorperazine 25 mg suppositories every 4 h, starting 30 min before the chemotherapy. They were crossed over for the next chemotherapy cycle. To enable analysis of 100 patients who had received identical chemotherapy in each course, 136 patients were randomised. Patients experienced a higher grade of nausea on domperidone (P = 0.05). Only 18% of patients vomited on domperidone and 14% on prochlorperazine, but the number of vomits was higher on domperidone (P = 0.003) and the duration was significantly increased (P = 0.02). Patients experienced significantly more diarrhoea on domperidone (P < 0.0001), although it was predominantly mild. Patients were significantly more sedated on prochlorperazine on the second course (P = 0.006), but not on the first course (P = 0.9). More patients preferred their second course (P < 0.0001), and were significantly less anxious (P = 0.0002). Patients reported tolerating their treatment similarly for both antiemetics, but more patients preferred prochlorperazine (P = 0.003), mainly due to reductions in nausea and vomiting and other side-effects, particularly diarrhoea.

Intraventricular administration of haloperidol or chlorpromazine produces catalepsy and blocks apomorphine-induced stereotypic behavior. Low intraventricular doses of domperidone, sulpiride and spiperone, equally cataleptogenic as haloperidol or chlorpromazine, augment rather than diminish stereotypic behavior produced by subsequent apomorphine treatment. The resultant stereotypic behavior continues even while the animal is in a rigid cataleptic posture and is marked by persistent gnawing and licking. Prior to the induction of catalepsy and after recovery from it, mice display the entire range of typical apomorphine-induced behavior including sniffing, climbing, gnawing, and licking. This animal model may be related to the clinical observation of the coexistence of tardive dyskinesia and drug-induced Parkinsonism in individual patients.

No major intraoperative complications were experienced, and there was no recurrence of gastroesophageal reflux during a postoperative follow-up period of 12 months. The parents' final subjective evaluation of the outcomes 12 months after surgery was positive in 44 cases and negative in 4 cases.

Respiratory activity was studied in adult rats during light halothane anesthesia. Dopamine agonists and antagonists were injected intracerebroventricularly (i.c.v.) or systemically. The respiratory parameters were recorded after exposure to O2 or to CO2 in O2. Apomorphine (i.c.v. 300 microgram) induced a biphasic response with an initial decrease in respiratory frequency (f) followed by pronounced tachypnoea after 5 min. The changes in tidal volume (VT) showed an inverse pattern. When apomorphine was administered into the fourth ventricle, only the later phase of the biphasic response was observed. Haloperidol (2 mg/kg i.p.) antagonized the apomorphine-induced response in contrast to domperidone (2 mg/kg i.v.), a dopamine receptor blocking agent which does not pass the blood brain barrier. Administered i.c.v., haloperidol as well as domperidone induced a decrease in f while VT was increased. The same response was observed after the presynaptic dopamine receptor agonist 3-PPP, 3-(3-hydroxyphenyl)-N-n-propylpiperidine. Hypercapnea was found to decrease the tachypnea in apomorphine-treated animals. Apomorphine also induced a decrease in blood pressure and heart rate, which was not reversed by haloperidol. It is concluded that there is a centrally located, tonically activated dopamine system involved in respiratory regulation. The predominant effect seems to be of a respiratory stimulating nature. The possible role of presynaptic and different postsynaptic dopamine receptor mechanisms is discussed.