Figure 1.
Figure 1.

Diagram showing the schedule of the uterine strips treatment with acetylcholine; salbutamol, a selective agonist of β2-adrenoceptors; BRL 37344, a selective agonist of β3-adrenoceptors; butoxamine, a selective antagonist of β2-adrenoceptors; propranolol, a non-selective antagonist of β1- and β2–adrenoceptors and bupranolol, a nonselective antagonist of β1–, β2–, and β3–adrenoceptors. Concentrations of the examined substances are expressed in moles.

 


Figure 2.
Figure 2.

Representative diagrams showing contractile activity of the porcine myometrial strips collected on d 12–14 of pregnancy; (A) spontaneous, regular activity of untreated strips; (B) the effect of increasing (10–9 to 10–5 M) concentrations of salbutamol (SAL); and (C) the effect of increasing (10–9 to 10–5 M) concentrations of BRL 37344 (BRL).

 


Figure 3.
Figure 3.

The effect of increasing (10–9 to 10–5 M) concentrations of salbutamol (Sal), a selective agonist of β2-adrenoceptors and BRL 37344 (BRL), a selective agonist of β3-adrenoceptors on the tension (A), frequency (B), and amplitude (C) of contractions of the porcine myometrial strips collected in the peri-implantation period (d 12 to 14 of the pregnancy). The results calculated for a 10 min period after treatments were expressed as a percentage (mean ± SD; n = 8) of the tension, amplitude, and frequency determined for a 10 min period before agonists administration and accepted as 100% (solid horizontal line). #P < 0.05; ##P < 0.01; ###P < 0.001 indicate significant differences compared to 10 min pretreatment period. **P < 0.01; ***P < 0.001 indicate significant differences between agonists used at the same concentrations.

 


Figure 4.
Figure 4.

The influence of butoxamine (But; 10–4 M), a selective antagonist of β2-adrenoceptors on changes in the tension (A), frequency (B), and amplitude (C) induced by increasing (10–9 to 10–5 M) concentrations of salbutamol, a selective agonist of β2-adrenergic receptors or BRL 37344 (BRL), a selective agonist of β3-adrenoceptors in the porcine myometrial strips collected in the peri-implantation period. The results calculated for a 10 min period after treatments were expressed as a percentage (mean ± SD; n = 8) of the tension, amplitude, and frequency determined for a 10 min period before butoxamine and salbutamol or BRL 37344 administration and accepted as 100% (solid horizontal line). #P < 0.05; ##P < 0.01; ###P < 0.001 indicate significant differences compared to 10 min pretreatment period. *P < 0.05; **P < 0.01; ***P < 0.001 indicate significant differences between agonists used at the same concentrations.

 


Figure 5.
Figure 5.

The influence of propranolol (Pro; 10–4 M), an antagonist of β1– and β2–adrenoceptors on changes in the tension (A), frequency (B), and amplitude (C) induced by increasing (10–9 to 10–5 M) concentrations of salbutamol, a selective agonist of β2-adrenergic receptors or BRL 37344 (BRL), a selective agonist of β3-adrenoceptors in the porcine myometrial strips collected in the peri-implantation period. The results were calculated for a 10 min period after treatments were expressed as a percentage (mean ± SD; n = 8) of the tension, amplitude and frequency determined for a 10 min period before propranolol and salbutamol or BRL 37344 administration and accepted as 100% (solid horizontal line). #P < 0.05; ##P < 0.01; ###P < 0.001 indicate significant differences compared to 10 min pretreatment period. *P < 0.05; **P < 0.01 indicate significant differences between agonists used at the same concentrations.

 


Figure 6.
Figure 6.

The influence of bupranolol (Bup; 10–4 M), an antagonist of β1–, β2–, and β3– adrenoceptors on changes in the tension (A), frequency (B), and amplitude (C) induced by increasing (10–9 to 10–5 M) concentrations of salbutamol, a selective agonist of β2-adrenergic receptors or BRL 37344 (BRL), a selective agonist of β3-adrenoceptors in the porcine myometrial strips collected in peri-implantation period. The results calculated for a 10 min period after treatments were expressed as a percentage (mean ± SD; n = 8) of the tension, amplitude and frequency determined for 10 min period before bupranolol and salbutamol or BRL 37344 administration and accepted as 100% (solid horizontal line). #P < 0.05; ##P < 0.01; ###P < 0.001 indicate significant differences compared to 10 min pretreatment period. *P < 0.05; **P < 0.01; ***P < 0.001 indicate significant differences between agonists used at the same concentrations.