Influence of PLC and MLCK inhibitors and the role of L-calcium channels in the cat pulmonary vascular bed

1995 ◽  
Vol 269 (4) ◽  
pp. L507-L513 ◽  
Author(s):  
A. D. Kaye ◽  
B. D. Nossaman ◽  
I. N. Ibrahim ◽  
P. J. Kadowitz
Keyword(s):  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Kinase Inhibitor ◽  
Bay K 8644 ◽  
Ang Ii ◽  
Arterial Perfusion ◽  
Vascular Bed ◽  
Pressor Responses ◽  
Pulmonary Vascular Bed

The effects of U-73122, a phospholipase C (PLC) inhibitor, on pressor responses to angiotensin II (ANG II), norepinephrine (NE), serotonin (5-HT), BAY K 8644, and the thromboxane A2 (TxA2) mimic, U-46619, were studied in the pulmonary vascular bed of the intact-chest cat. Under conditions of constant lobar blood flow, injections of ANG II, NE, 5-HT, U-46619, and the calcium channel opener, BAY K 8644, into the lobar arterial perfusion circuit caused dose-related increases in lobar arterial pressure, which were reproducible with respect to time. Infusion of U-73122, a PLC inhibitor, into the perfused lobar artery at 10–100 micrograms/kg for 10 min significantly reduced responses to ANG II, serotonin, and NE; however, U-73122 did not alter responses to BAY K 8644 or to U-46619. In a separate series of animals, the effects of the myosin light chain kinase inhibitor, KT-5926, were investigated, and after infusion of KT-5926 into the perfused lobar artery at 1–2 micrograms/kg for 10 min, responses to ANG II, NE, 5-HT, BAY K 8644, and U-46619 were reduced significantly. In a final series of experiments, the effects of the L-type calcium channel blocker, nicardipine, were investigated, and infusion of the L-type calcium channel blocker into the perfused lobar artery at 0.5-1 microgram/kg for 10 min reduced responses to ANG II, BAY K 8644, and NE. However, nicardipine did not alter pressor responses to 5-HT or the TxA2 mimic, U-46619.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of phospholipase A2, 12-lipoxygenase, and cyclooxygenase inhibitors in the feline pulmonary bed

1997 ◽  
Vol 272 (4) ◽  
pp. L573-L579 ◽  
Author(s):  
A. D. Kaye ◽  
B. D. Nossaman ◽  
D. E. Smith ◽  
I. N. Ibrahim ◽  
J. D. Imig ◽  
...  
Keyword(s):  
Phospholipase A2 ◽  
Phospholipase C ◽  
Bay K 8644 ◽  
Cyclooxygenase Inhibitors ◽  
Ang Ii ◽  
Lipoxygenase Inhibitor ◽  
Arterial Perfusion ◽  
Vascular Bed ◽  
Phospholipase A2 Inhibitor ◽  
Pulmonary Vascular Bed

The effects of phosphonofluoridic acid, methyl-5,8,11,14-eicosatetraenyl ester (MAFP), a phospholipase A2 inhibitor, on pressor responses to angiotensin II (ANG II), norepinephrine (NE), serotonin (5-HT), the calcium channel opener BAY K 8644, and the thromboxane A2 mimic U-46619 were studied in the pulmonary vascular bed of the intact-chest cat. Under conditions of constant lobar blood flow, injections of ANG II, NE, 5-HT, U-46619, and BAY K 8644 into the lobar arterial perfusion circuit caused dose-related increases in lobar arterial pressure that were reproducible with respect to time. Infusion of MAFP into the perfused lobar artery at doses of 100 to 300 microg/kg for 10 min significantly reduced vasoconstrictor responses to ANG II; however, the phospholipase A2 inhibitor did not alter vasoconstrictor responses to BAY K 8644, 5-HT, NE, or U-46619. The combination of the higher dose of the phospholipase A2 inhibitor MAFP with the phospholipase C inhibitor U-73122 significantly affected vasoconstrictor responses to ANG II, NE, and 5-HT but not to BAY K 8644. In a separate series of animals, the effects of a lipoxygenase inhibitor, baicalein, were investigated. Infusion of baicalein into the perfused lobar artery at doses of 100 microg/kg for 10 min significantly reduced vasoconstrictor responses to ANG II but not the vasoconstrictor responses to BAY K 8644, 5-HT, NE, or U-46619. In a final series of experiments, the effects of a cyclooxygenase inhibitor, meclofenamate, were investigated, and intravenous injection of the meclofenamate at a dose of 2.5 mg/kg did not significantly affect vasoconstrictor responses to ANG II, 5-HT, BAY K 8644, NE, or U-46619. These data provide support for the hypothesis that pulmonary vasopressor responses to ANG II are mediated, in part, by the activation of phospholipase A2, phospholipase C, and the lipoxygenase pathway in the pulmonary vascular bed of the cat.

Verapamil blockade of pressor and uterine responses to AVP-OT analogue, oxypressin

1988 ◽  
Vol 254 (1) ◽  
pp. R75-R77
Author(s):  
D. Gazis ◽  
G. Gonzalez ◽  
M. Mendlowitz
Keyword(s):  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Pressor Response ◽  
Pressor Responses ◽  
Significant Difference

The effects of the calcium channel blocker verapamil on simultaneously recorded uterine and pressor responses to the equipotent (in eliciting these responses) oxytocin-vasopressin analogue, oxypressin, were studied in urethan-anesthetized and pentolinium- and indomethacin-treated rats during injections and infusions of this analogue. Doses of verapamil that almost completely blocked the pressor response to infused oxypressin had no effect on a pressor response to injected oxypressin of equal magnitude. Larger doses of verapamil blocked the pressor response to injected oxypressin somewhat. Uterine responses were only marginally affected by these doses of verapamil, and there was no significant difference between infusion and injection or between estrus and diestrus.

Depolarization-stimulated cholecystokinin secretion is mediated by L-type calcium channels in STC-1 cells

1996 ◽  
Vol 270 (2) ◽  
pp. G287-G290 ◽  
Author(s):  
A. W. Mangel ◽  
L. Scott ◽  
R. A. Liddle
Keyword(s):  
Calcium Channels ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Single Channel ◽  
Bay K 8644 ◽  
Ic50 Value ◽  
Single Channel Currents ◽  
Dose Dependent ◽  
Cck Release

To examine the role of calcium channels in depolarization-activated cholecystokinin (CCK) release, studies were performed in an intestinal CCK-secreting cell line, STC-1. Blockade of potassium channels with barium chloride (5 mM) increased the release of CCK by 374.6 +/- 46.6% of control levels. Barium-induced secretion was inhibited by the L-type calcium-channel blocker, nicardipine. Nicardipine (10(-9)-10(-5) M) produced a dose-dependent inhibition in barium-stimulated secretion with a half-maximal inhibition (IC50) value of 0.1 microM. A second L-type calcium-channel blocker, diltiazem (10(-9)-10(-4) M), also inhibited barium-induced CCK secretion with an IC50 value of 5.1 microM. By contrast, the T-type calcium-channel blocker, nickel chloride (10(-7)-10(-8) M), failed to significantly inhibit barium-induced CCK secretion. To further evaluate a role for L-type calcium channels in the secretion of CCK, the effects of the L-type calcium channel opener, BAY K 8644, were examined. BAY K 8644 (10(-8)-10(-4) M) produced a dose-dependent stimulation in CCK release with a mean effective concentration value of 0.2 microM. Recordings of single-channel currents from inside-out membrane patches showed activation of calcium channels by BAY K 8644 (1 microM), with a primary channel conductance of 26.0 +/- 1.2 pS. It is concluded that inhibition of potassium channel activity depolarizes the plasma membrane, thereby activating L-type, but not T-type, calcium channels. The corresponding influx of calcium serves to trigger secretion of CCK.

Chronic treatment by the calcium channel blocker ± PN 200-110 in the rat counteracts the stimulations of pituitary weight, prolactin release and pituitary C-kinase activity induced by a chronic estradiol treatment, in vivo

1990 ◽  
Vol 122 (3) ◽  
pp. 403-408
Author(s):  
Ph. Touraine ◽  
P. Birman ◽  
F. Bai-Grenier ◽  
C. Dubray ◽  
F. Peillon ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Plasma Prolactin ◽  
Estradiol Treatment ◽  
Kinase C ◽  
Protein Kinase C Activity

Abstract In order to investigate whether a calcium channel blocker could modulate the protein kinase C activity in normal and estradiol pretreated rat pituitary, female Wistar rats were treated or not (controls) with ± PN 200-110 (3 mg · kg−1 · day−1, sc) for 8 days or with estradiol cervical implants for 8 or 15 days, alone or in combination with PN 200-110 the last 8 days. Estradiol treatment induced a significant increase in plasma prolactin levels and pituitary weight. PN 200-110 administered to normal rats did not modify these parameters, whereas it reduced the effects of the 15 days estradiol treatment on prolactin levels (53.1 ± 4.9 vs 95.0 ±9.1 μg/l, p<0.0001) and pituitary weight (19.9 ± 0.4 vs 23.0 ± 0.6 mg, p <0.001), to values statistically comparable to those measured after 8 days of estradiol treatment. PN 200-110 alone did not induce any change in protein kinase C activity as compared with controls. In contrast, PN 200-110 treatment significantly counteracted the large increase in soluble activity and the decrease in the particulate one induced by estradiol between day 8 and day 15. We conclude that PN 200-110 opposed the stimulatory effects of chronic in vivo estradiol treatment on plasma prolactin levels and pituitary weight and that this regulation was related to a concomitant modulation of the protein kinase C activity.

Effects of an Antihypertensive Combination in Japanese Hypertensive Outpatients Based on the Long-Acting Calcium Channel Blocker Benidipine on Vascular and Renal Events: A Sub-Analysis of the COPE Trial

2020 ◽  
Vol 16 ◽  
Author(s):  
Seiji Umemoto ◽  
Toshio Ogihara ◽  
Masunori Matsuzaki ◽  
Hiromi Rakugi ◽  
Kazuyuki Shimada ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Channel Blocker ◽  
Rank Test ◽  
Vascular Events ◽  
Treatment Groups ◽  
Β Blocker ◽  
The Difference ◽  
Long Acting

Background: In the trial known as COPE (Combination Therapy of Hypertension to Prevent Cardiovascular Events) three benidipine (a calcium channel blocker; CCB) regimens were compared. Hypertensive Japanese outpatients aged 40–85 years (n=3,293) who did not achieve the target blood pressure of <140/90 mmHg with benidipine 4 mg/day were treated with the diuretic thiazide (n=1,094) or a β-blocker (n=1,089) or an additional angiotensin receptor blocker (ARB; n=1,110). A significantly higher incidence of hard cardiovascular composite endpoints and of fatal or non-fatal strokes was observed in the benidipine-β-blocker group compared to the benidipine-thiazide group. Objective and Methods: We further evaluated the treatment effects of the three benidipine-based regimens on vascular and renal events in a sub-analysis of the COPE patients. Results: A total of 10 vascular events (0.8 per 1,000 person-years) including one aortic dissection (0.1 per 1,000 person-years) and nine cases of peripheral artery disease (0.8 per 1,000 person-years) were documented, as was a total of seven renal events (0.6 per 1,000 person-years). No significant differences in vascular and renal events were revealed among the three treatment groups: vascular events p=0.92 renal events p=0.16 log-rank test. Conclusions: Blood pressure-lowering therapy with benidipine combined with an ARB, β-blocker, or thiazide was similarly effective in the prevention of vascular and renal events in hypertensive outpatients, although there is no enough these events to compare the difference in the three treatment groups.

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