Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085383 (hypocapnia)
 1,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ketanserin, a 5HT2- and alpha 1-receptor antagonist, decreases blood pressure by decreasing systemic vascular resistance without causing reflex cardiac stimulation, while cardiac output remains unchanged. To date, little is known about the effects of ketanserin on cerebral haemodynamics and cerebral metabolism. According to a recently published study, ketanserin seems not to impair cerebral blood flow autoregulation in man. The present study was designed to investigate the influence of ketanserin on cerebral circulation and metabolism, and the cerebrovascular response to CO2 in man. METHODS. Twenty male patients between 44 and 67 years of age who were scheduled for coronary artery bypass surgery were randomly allocated to one of two groups. In group 1 measurements were performed after induction of anaesthesia during normocapnia (p(a) CO2 approximately 40 mm Hg) and hypocapnia (p(a) CO2 approximately 30 mm Hg). Then, ketanserin was given at a bolus dose of 0.3 mg.kg-1 followed by an infusion of 0.06 mg.kg-1.h-1 and measurements were repeated under hypocapnic and normocapnic conditions. Patients of group 2 were hyperventilated at first, then normoventilated. Afterwards, ketanserin was administered at the above-mentioned dose and measurements were again performed during normocapnia and hypocapnia. Cerebral blood flow (CBF) was measured using the argon wash-in technique. Cerebral venous blood was obtained from a catheter in the superior bulb of the right internal jugular vein. Cerebral perfusion pressure (CPP) was calculated by subtracting jugular bulb pressure from mean arterial pressure and cerebral vascular resistance (CVR) by dividing CPP by CBF. Cerebral metabolic rates of oxygen, glucose, and lactate were calculated by multiplying the arterial-cerebral venous oxygen and substrate differences by CBF. RESULTS AND DISCUSSION. Ketanserin decreased CPP by 16% to about 60 mm Hg. Cerebral blood flow remained unchanged as a result of an insignificant decline in CVR. Hyperventilation increased CVR by 32%, while CBF decreased by 27% to the same value that had been obtained during hypocapnia without ketanserin. The percentage changes in CBF per mm Hg change in CO2 were 1.45%/mm Hg (group 1 and 2.91%/mm Hg (group 2), respectively, without ketanserin and 1.98%/mm Hg and 2.22%/mm Hg with ketanserin. As CO2-responsiveness with ketanserin was higher in group 1 but lower in group 2 than without ketanserin, the direction in which ventilation was changed rather than ketanserin was responsible for these changes in CO2-responsiveness. Neither during normocapnia nor during hypocapnia did ketanserin have any effects on cerebral metabolic activity. Thus, it can be concluded that ketanserin does not impair CBF regulation and metabolism and that cerebral vascular responsiveness to hypocapnia is preserved.
 ...
PMID:[Cerebral effects of ketanserin. The influence on hemodynamics and brain metabolism]. 144 11

The aim of this study was to examine the influence of ketanserin, a 5-hydroxytryptamine antagonist antihypertensive agent, on the relationship between cerebral blood flow (CBF) and middle cerebral artery flow velocity (Vmean MCA) and to compare Doppler-sonographic indices of downstream resistance (pulsatility index, PI; resistance index, RI) with calculations of cerebrovascular resistance (CVR) in 17 male patients under fentanyl/midazolam anesthesia. CBF was measured with the Kety-Schmidt technique using argon as a tracer. Cerebral perfusion pressure (CPP) was calculated as the difference between mean arterial pressure (MAP) and jugular bulb pressure. Measurements of Vmean MCA and determinations of PI and RI were performed by use of a 2-MHz transcranial Doppler ultrasound device. All variables were measured at normo- and moderate hypocapnia before and after intravenous (i.v.) bolus administration of 0.3 mg/kg ketanserin followed by an infusion of 0.06 mg.kg-1.h-1. Ketanserin changed neither average CBF nor Vmean MCA. The CO2 reactivity of Vmean MCA was significantly lower than the CO2 reactivity of CBF (P < 0.01); however, ketanserin did not change the relationship between CBF and Vmean MCA. During hypocapnia, CVR as well as PI and RI significantly increased (P < or = 0.01), indicating consistent directional changes in arteriolar resistance and flow velocity pulsatility. In contrast, after i.v. administration of ketanserin, CVR decreased (P < 0.05), whereas both Doppler-derived indices increased (P < 0.01). These results suggest that ketanserin in a clinically relevant dose does not alter the validity of serial Vmean MCA measurements as an index of global CBF and that ketanserin does not change the diameter of middle cerebral arteries (MCAs). Doppler-derived indices of pulsatility and resistance, which are supposed to estimate changes in downstream resistance, reflect changes, after administration of ketanserin, in systemic hemodynamics rather than changes in CVR.
 ...
PMID:Effect of ketanserin on global cerebral blood flow and middle cerebral artery flow velocity. 780 2