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Biomedical subjects

L Vacek

Publications and source records attributed to L Vacek.

11 recordsLinked to original sources
PubMed1989

Regional differences of cardiovascular effects of diltiazem in the rat.

The dose-response relations of the central and peripheral effects of diltiazem were studied in 26 anaesthetized rats. Measured were the heart rate (HR), atrioventricular conduction time (PR), mean arterial blood pressure (BP), carotid and renal blood flow (Fc, Fr) and the corresponding relative regional resistance (RRc, RRr). The effects were evaluated by their maxima regularly reached 15-20 s after the i.v. bolus administration. The minimum dose which produced a significant HR decrease and PR prolongation were 0.4 and 2.0 mg/kg, respectively. In the mg/kg dose range a transient second degree AV block was regularly recorded. The lethal dose (cardiac arrest) was 20 mg/kg. BP significantly already decreased after 4 micrograms/kg. The dose-dependent decrease of Fr matched the hypotensive effect in the whole range due to unchanged RRr. In contrast Fc invariably increased at lower doses reflecting the RRc decay. Only in the mg/kg dose range Fc decreased in accord with BP since RRc dropped to a constant value (50% of control) with each administration. The peripheral reactions were significantly augmented in rats with renovascular hypertension. It is concluded that, in this model, the peripheral effects of diltiazem evidently surpass the central ones. The regional difference between the inert renal and responsive carotid vasculature might be due to a different mode of regulation of the respective vascular tone, hypothetically reflecting different density of membrane, potential-dependent Ca2+ channels.

Animals↗
PubMed1989

The effect of prostaglandins E2 and F2 alpha on carotid blood flow in rats with renovascular hypertension.

The effect of i.v. bolus administration of PGE2 and PGF2 alpha on carotid blood flow (Q) and mean arterial blood pressure (MAP) was recorded in 21 anaesthetized normotensive control (N) and 12 rats with 1K1C renovascular hypertension (RH). From the measured parameters the regional vascular impedance (PVI) and the change in blood volume were calculated. In normotensive animals both PGs elicited a dose-dependent initial fast increase of Q (threshold dose 0.4 ng/kg) and a decrease of MAP and PVI (threshold dose 0.4 micrograms/kg). Subsequently, Q decreased below the initial level. MAP and PVI remained depressed after E2 but increased after F2 alpha. The time course of the Q and MAP responses was analyzed in more detail at a standard dose 4 micrograms/kg. The average time to peak of the first phase was 12 s and of the second approximately 80 s. The initial levels of Q and MAP were reestablished within 3 to 4 minutes. The total volume of carotid blood flow obtained by planimetric integration was unaltered after F2 alpha but depressed after E2. In hypertensive animals both phases of the response to E2 were significantly retarded and the Q response was nearly abolished. On the other hand, the time course of the reaction to F2 alpha was unchanged but the magnitude of the second pressoric phase was reduced. Thus, the capacity of the carotid vascular bed to dilate remains the same in RH while the ability to constrict is limited. It is concluded that the response of MAP and Q to both PGs are relatively independent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The occurrence of endothelial cells in the blood in deep venous inflammation].

The number of anuclear residues of endothelial cells in the blood stream was investigated in 22 patients suffering from deep phlebitis and no other disease. The level of endothelaemia in these patients was in all instances higher than in 24 healthy subjects. Assessment of the endothelaemia in patients with deep phlebitis makes more accurate assessment of the diagnosis and the follow-up of regression of the disease possible.

Endothelium, Vascular↗
PubMed1979

Early stages of experimental atheromatosis.

In female Wistar rats, fed an atherogenic diet, the early changes of serum lipids and the deviation of the vasomotor response to adrenaline and acetylcholine were compared with morphological manifestations. It has been found that the first sign may be detected as the shift in serum lipoproteins and lipids just in a few days. Merging and decrease of alpha-lipoproteins and an increase of the beta-lipoprotein fraction proved as the most sensitive indicator. In the course of several weeks, an alteration of hemodynamic response to adrenaline and acetylcholine occured. The animals revealed a diminished depressoric response to acetylcholie, whereas their blood pressure response to adrenaline in the pressoric phase was decreased but the depressoric phase was markedly expressed. The morphological impairment of the vascular system followed with a delay of several months, although a lipoid infiltration of the liver appeared after 6 weeks of the atherogenic dietary regimen.

Acetylcholine↗
PubMed1978

Blood pressure response to bolus administration of vasoactive drugs in the rat.

The time course of systemic blood pressure response in normotensive anaesthetized rats was studied after a bolus administration of standard doses (0.4 microgram/kg) of noradrenaline, adrenaline, isoprenaline, acetylcholine, serotonin, bradykinin, and histamine. The single stimulus of a vasoactive agent elicits a blood pressure deviation with typical phasing. The time dimension of the individual wave is less variable and less dose dependent than their amplitude. Under the given experimental conditions the blood pressure response is predominantly determined by the peripheral vasomotor reactions; the cardiac component is of minor importance. Though the overall responses to the individual drugs are quite characteristic, they seem to comprise several common components. Thus the peripheral vascular system is supposed to consist of different regulatory subsystems which take part in the systemic blood pressure control by typically timed responses. The pattern of the reaction is then given by their unequal combination and various intensity.

Animals↗
PubMedDate not supplied

[Aging changes in conjunctival blood vessels].

The relation of the changes in the conjunctival blood vessels to the age were studied in a group of 217 persons aged 20 to 79 years. All persons suffering from arterial hypertension, diabetes, systemic diseases and manifested forms of arteriosclerosis were excluded. It has been proved that examination of the conjunctival blood vessels by means of the slot-lamp facilitates the study of the changes in the microscopic blood vessels in relation to the age. Most conspicuous was the increase of the meander course of the blood vessels, also the increasing number of blood vessels is more frequent in the group of older persons. Clusters of vessels and a narrowing of the diameter of the arterioles was seen only in persons over fifty years of age. The "upright" course of the arterioles was found only in individual cases and without any special dependence to age. Sacculations on the small veins and microaneurysms on the arterioles were not observed in any of the examined group of healthy persons.

Adult↗